Thanks to a hand-written list Jacob Derks transcribed, a list I recently received from my 2nd cousin once removed, I now know of the following children:

1st child: Derk - born 5 Nov 1857.  This means that Janna, Jacob's 1st wife, was with child when married on 18 April 1857 and when traversing across the ocean on the Devonshire.  Derk died on 27 Feb 1858.

2nd child: Jobtje (Jessie) - born 23 Dec 1858.  Jessie never married.

3rd child: Gerritje (Carrie) - born 9 Feb 1860.  Carrie never married.

4th child: Nantje (Nettie) - born 26 Aug 1861. 

5th child: Derk - born 15 July 1863.  This is the time that Janna died: on 26 July 1863.  Though it is not written here, I would suspect there were complications with the delivery and the baby was born stillborn or died shortly thereafter. 

Here the list backdates to list the children inherited by marriage to Gezina Rotmans, Jacob's 2nd wife.

Inherited Child 1: Johana - born 9 April 1852.

Inherited Child 2: Rika - born 5 Nov 1854.

Inherited Child 3: Janna - born 7 July 1857.

Inherited Child 4: Miena - born 5 June 1860.

Inherited Child 5: Finie - born 24 March 1863.

Then the list continues with blood relation...

6th child: Tryntje (Frances) - born 11 May 1866.

7th child: Derktje (Della) - born 9 Sept 1868.  Della died 5 Jan 1872.

8th child: Gezina (Zena) - born 25 Jan 1871.  Zena died on 28 July 1871.

Jacob's 2nd wife Gezina died 12 April 1874.

9th child: Derk Jakobs - born 23 April 1879.

All dates transcribed by Jacob.  This would have been recorded between the time Jacob lost his 2nd wife Gezina (1874) and the time he remarried Jennie (1877).  All entries are made in pen save the final entry which is in pencil: an obvious addition.