SCHEDULE 13G

Under the Securities Exchange Act of 1934
(Amendment No. 2)*

(Name of Issuer)

(Title of Class of Securities)

(CUSIP Number)

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

*The remainder of this cover page shall be filled out for a reporting person's initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter the disclosures provided in a prior cover page.

The information required in the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

(1)         This Schedule 13G is filed by MDV VII, L.P., MDV VII Leaders’ Fund, L.P., MDV ENF VII(A), L.P., MDV ENF VII(B), L.P. (collectively, “MDV”), Seventh MDV Partners, L.L.C. (“Seventh”), William Ericson, Nancy Schoendorf and Jonathan Feiber (collectively, the “Fund Entities”).  The Fund Entities expressly disclaim status as a “group” for purposes of this Schedule 13G.

(2)         Shares directly held by MDV VII, L.P.  William Ericson,  Nancy Schoendorf and Jonathan Feiber are managing members of Seventh, the general partner of MDV.  Each of William Ericson, Nancy Schoendorf, Jonathan Feiber and Seventh may be deemed to share voting and dispositive power over the shares held by MDV.

(3)         This percentage is calculated based on 116,249,978 shares of the Issuer’s stock outstanding (as of October 31, 2017), as set forth in the Issuer’s most recent 10-Q, filed with the Securities and Exchange Commission on November 2, 2017.

2

(1)         This Schedule 13G is filed by MDV VII, L.P., MDV VII Leaders’ Fund, L.P., MDV ENF VII(A), L.P., MDV ENF VII(B), L.P. (collectively, “MDV”), Seventh MDV Partners, L.L.C. (“Seventh”), William Ericson,  Nancy Schoendorf and Jonathan Feiber (collectively, the “Fund Entities”).  The Fund Entities expressly disclaim status as a “group” for purposes of this Schedule 13G.

(2)         Shares directly held by MDV VII, L.P. as nominee for MDV VII Leaders’ Fund, L.P.  William Ericson,  Nancy Schoendorf and Jonathan Feiber are managing members of Seventh, the general partner of MDV.  Each of William Ericson,  Nancy Schoendorf, Jonathan Feiber and Seventh may be deemed to share voting and dispositive power over the shares held by MDV. 

(3)         This percentage is calculated based on 116,249,978 shares of the Issuer’s stock outstanding (as of October 31, 2017), as set forth in the Issuer’s most recent 10-Q, filed with the Securities and Exchange Commission on November 2, 2017.

3

(1)         This Schedule 13G is filed by MDV VII, L.P., MDV VII Leaders’ Fund, L.P., MDV ENF VII(A), L.P., MDV ENF VII(B), L.P. (collectively, “MDV”), Seventh MDV Partners, L.L.C. (“Seventh”), William Ericson,  Nancy Schoendorf and Jonathan Feiber (collectively, the “Fund Entities”).  The Fund Entities expressly disclaim status as a “group” for purposes of this Schedule 13G.

(2)         Shares directly held by MDV VII, L.P. as nominee for MDV ENF VII(A), L.P.  William Ericson, Nancy Schoendorf and Jonathan Feiber are managing members of Seventh, the general partner of MDV.  Each of William Ericson, Nancy Schoendorf, Jonathan Feiber and Seventh may be deemed to share voting and dispositive power over the shares held by MDV. 

(3)         This percentage is calculated based on 116,249,978 shares of the Issuer’s stock outstanding (as of October 31, 2017), as set forth in the Issuer’s most recent 10-Q, filed with the Securities and Exchange Commission on November 2, 2017.

4

(1)         This Schedule 13G is filed by MDV VII, L.P., MDV VII Leaders’ Fund, L.P., MDV ENF VII(A), L.P., MDV ENF VII(B), L.P. (collectively, “MDV”), Seventh MDV Partners, L.L.C. (“Seventh”), William Ericson,  Nancy Schoendorf and Jonathan Feiber (collectively, the “Fund Entities”).  The Fund Entities expressly disclaim status as a “group” for purposes of this Schedule 13G.

(2)         Shares directly held by MDV VII, L.P. as nominee for MDV ENF VII(B), L.P.  William Ericson, Nancy Schoendorf and Jonathan Feiber are managing members of Seventh, the general partner of MDV.  Each of William Ericson, Nancy Schoendorf, Jonathan Feiber and Seventh may be deemed to share voting and dispositive power over the shares held by MDV. 

(3)         This percentage is calculated based on 116,249,978 shares of the Issuer’s stock outstanding (as of October 31, 2017), as set forth in the Issuer’s most recent 10-Q, filed with the Securities and Exchange Commission on November 2, 2017.

5

(1)   This Schedule 13G is filed by MDV VII, L.P., MDV VII Leaders’ Fund, L.P., MDV ENF VII(A), L.P., MDV ENF VII(B), L.P. (collectively, “MDV”), Seventh MDV Partners, L.L.C. (“Seventh”), William Ericson,  Nancy Schoendorf and Jonathan Feiber (collectively, the “Fund Entities”).  The Fund Entities expressly disclaim status as a “group” for purposes of this Schedule 13G.

(2)   Shares directly held by MDV VII, L.P. and by MDV VII, L.P. as nominee for MDV VII Leaders’ Fund, L.P., MDV ENF VII(A), L.P., and MDV ENF VII(B), L.P.  William Ericson, Nancy Schoendorf and Jonathan Feiber are managing members of Seventh, the general partner of MDV.  Each of William Ericson,  Nancy Schoendorf, Jonathan Feiber and Seventh may be deemed to share voting and dispositive power over the shares held by MDV. 

(3)   This percentage is calculated based on 116,249,978 shares of the Issuer’s stock outstanding (as of October 31, 2017), as set forth in the Issuer’s most recent 10-Q, filed with the Securities and Exchange Commission on November 2, 2017.

6

(1)   This Schedule 13G is filed by MDV VII, L.P., MDV VII Leaders’ Fund, L.P., MDV ENF VII(A), L.P., MDV ENF VII(B), L.P. (collectively, “MDV”), Seventh MDV Partners, L.L.C. (“Seventh”), William Ericson,  Nancy Schoendorf and Jonathan Feiber (collectively, the “Fund Entities”).  The Fund Entities expressly disclaim status as a “group” for purposes of this Schedule 13G.

(2)   Shares directly held by MDV VII, L.P. and by MDV VII, L.P. as nominee for MDV VII Leaders’ Fund, L.P., MDV ENF VII(A), L.P., and MDV ENF VII(B), L.P.  William Ericson, Nancy Schoendorf and Jonathan Feiber are managing members of Seventh, the general partner of MDV.  Each of William Ericson,  Nancy Schoendorf, Jonathan Feiber and Seventh may be deemed to share voting and dispositive power over the shares held by MDV.

(3)   This percentage is calculated based on 116,249,978 shares of the Issuer’s stock outstanding (as of October 31, 2017), as set forth in the Issuer’s most recent 10-Q, filed with the Securities and Exchange Commission on November 2, 2017.

7

(1)   This Schedule 13G is filed by MDV VII, L.P., MDV VII Leaders’ Fund, L.P., MDV ENF VII(A), L.P., MDV ENF VII(B), L.P. (collectively, “MDV”), Seventh MDV Partners, L.L.C. (“Seventh”), William Ericson,  Nancy Schoendorf and Jonathan Feiber (collectively, the “Fund Entities”).  The Fund Entities expressly disclaim status as a “group” for purposes of this Schedule 13G.

(2)   Shares directly held by MDV VII, L.P. and by MDV VII, L.P. as nominee for MDV VII Leaders’ Fund, L.P., MDV ENF VII(A), L.P., and MDV ENF VII(B), L.P.  William Ericson, Nancy Schoendorf and Jonathan Feiber are managing members of Seventh, the general partner of MDV.  Each of William Ericson,  Nancy Schoendorf, Jonathan Feiber and Seventh may be deemed to share voting and dispositive power over the shares held by MDV.

(3)   This percentage is calculated based on 116,249,978 shares of the Issuer’s stock outstanding (as of October 31, 2017), as set forth in the Issuer’s most recent 10-Q, filed with the Securities and Exchange Commission on November 2, 2017.

8

(1)   This Schedule 13G is filed by MDV VII, L.P., MDV VII Leaders’ Fund, L.P., MDV ENF VII(A), L.P., MDV ENF VII(B), L.P. (collectively, “MDV”), Seventh MDV Partners, L.L.C. (“Seventh”), William Ericson,  Nancy Schoendorf and Jonathan Feiber (collectively, the “Fund Entities”).  The Fund Entities expressly disclaim status as a “group” for purposes of this Schedule 13G. 

(2)   Includes options issued to William Ericson to purchase 187,500 shares of Common Stock of which 179,166 shares have vested or will become vested in 90 days.

(3)   Shares directly held by MDV VII, L.P. and by MDV VII, L.P. as nominee for MDV VII Leaders’ Fund, L.P., MDV ENF VII(A), L.P., and MDV ENF VII(B), L.P.  William Ericson,  Nancy Schoendorf and Jonathan Feiber are managing members of Seventh, the general partner of MDV.  Each of William Ericson,  Nancy Schoendorf, Jonathan Feiber and Seventh may be deemed to share voting and dispositive power over the shares held by MDV. 

(4)   This percentage is calculated based on 116,249,978 shares of the Issuer’s stock outstanding (as of October 31, 2017), as set forth in the Issuer’s most recent 10-Q, filed with the Securities and Exchange Commission on November 2, 2017.

9

Introductory Note:  This Statement on Schedule 13G is filed on behalf of 1) MDV VII, L.P., a limited partnership organized under the laws of the State of Delaware; 2) MDV VII Leaders’ Fund, L.P., a limited partnership organized under the laws of the State of Delaware; 3) MDV ENF VII(A), L.P., a limited partnership organized under the laws of the State of Delaware; 4) MDV ENF VII(B), L.P. (together with MDV VII, L.P., MDV VII Leaders’ Fund, L.P., and MDV ENF VII(A), L.P., “MDV”), a limited partnership organized under the laws of the State of Delaware; 5) Seventh MDV Partners, L.L.C. (“Seventh”), a limited liability company organized under the laws of the State of Delaware and the General Partner of MDV; 6) Nancy Schoendorf, a managing member of Seventh; 7) William Ericson, a managing member of Seventh; and 8) Jonathan Feiber, a managing member of Seventh; in respect of shares of Common Stock of Pacific Biosciences of California, Inc.

10

(1)         Seventh MDV Partners, L.L.C. serves as the general partner of MDV VII, L.P., MDV VII Leaders’ Fund, L.P., MDV ENF VII(A), L.P., and MDV ENF VII(B), L.P. and owns no securities of the Issuer directly.  William Ericson,  Nancy Schoendorf and Jonathan Feiber serve as managing members of Seventh MDV Partners, L.L.C. and own no securities of the Issuer directly.

(2)         This percentage is calculated based on 116,249,978 shares of the Issuer’s stock outstanding (as of October 31, 2017), as set forth in the Issuer’s most recent 10-Q, filed with the Securities and Exchange Commission on November 2, 2017.

11

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

Dated:  February 14, 2018

EXHIBITS

A:            Joint Filing Agreement

12

EXHIBIT A

JOINT FILING AGREEMENT

We, the undersigned, hereby express our agreement that the attached Schedule 13G (or any amendments thereto) relating to the Common Stock of Pacific Biosciences of California, Inc. is filed on behalf of each of us.

Dated:  February 14, 2018

13