TRANSACTIONS 



OF 



THE ZOOLOGICAL SOCIETY 

 OF LONDON. 



I. The Development of the Starfish Solaster endeca Forbes. By James F. Gemmill, 

 M.A., M.D., B.Sc, F.Z.S., Lecturer in Fmhrijology, Glasgoio University, and in 

 Zoology, Glasgoio Provincial Training College. 



(Eeceived and read November 29, 1910.) 



[Plates I.-V.] 



COJTTENIS. 



Page 

 I. Stettciuee and Position 3 



II. Ovaries and Ova 4 



Arrangement and structure of the egg-tubes, 4 ; muscular tissue and sinus-spaces in 

 their walls, 4 ; relation of the latter to genital sinuses and htemal tissue, 5 ; growth 

 of the ova, 6 ; accumulation of yolk-granules, 6 ; yolk-nuclei, 7 ; follicle-cells, 7 ; 

 egg-ducts, 8. 



III. Mattteation, SPAWNiNa, Peetilization, &c 9 



Time of maturation, 9 ; season, &c. of spawning, 9 ; the ova in water, 10 ; membrane of 

 fertilisation, 11 ; cross-fertilisation, 11 ; early and later segmentation, 11 ; formation 

 of blastula by egression and of gastrula by invagination, 12; appearance of cilia, 12; 

 movements of blastula and gastrula, 13 ; hypenohyme, 13 ; chronology, 13. 



IV. External Charactbes, Movements, &c. dueins the Febb-swimming Period 14 



Elongation of gastrula, 14 ; formation of arms and of sucker, 14 ; preoral lobe and body of 

 larva, 14 ; formation of hydroporc, 14 ; closure of blastopore, 15 ; movements of the 

 larvse, 15; ciliation at anterior and posterior ends and over general surface, 15 ; 

 commencement of flexion and torsion of the preoral lobe, 16 ; first appearance extern- 

 ally of hydrocoele lobes and of aboral arm rudiments, 17 ; chronologj', 17. 



YOL. XX. — PART I. No. 1. — February, 1912. B 



