THE ANNALS 



AND 



MAGAZINE OF NATURAL HISTORY, 



No. 114. JUNE 1846. 



XLVII. — On the Development of the Ova of the Nudibranchiate 

 Mollusca. By John Reid^ M.D., Fellow of the Royal College 

 of Physicians of Edinburgh^ and Professor of Anatomy and 

 Medicine in the University of St. Andrews. 



[With a Plate.] 



The following observations upon the development of the Nudi- 

 branchiate Mollusca were made on the ova of the Doris bilameU 

 lata, Doris tuberculata, Goniodoris Barvicensis, Polycera quadri- 

 lineata, Dendronotus arbor escens, Doto coronata^, and a species 

 of Eolis having numerous flattened papillse^ depressed and im- 

 bricated, arranged in fifteen or sixteen distinct rows, which I 

 have not been able to refer to any of the species of that genus, 

 the descriptions of which have yet come under my notice. 



In the middle of last September I procured several specimens 

 of Polycera quadrilineata found together near low-water mark, in 

 each of which there was placed immediately beneath the external 

 integuments of the upper surface a large white mass, slightly 

 lobulated, lying behind and on each side of the heart, and pro- 

 longed forward as far as the external orifices of the reproductive 

 organs. Two pairs of the animals were kept in separate vessels 

 and daily supplied with fresh sea-water. Eight days after this 

 one of the pairs was seen in coitu, lying side by side, the head of 

 the one looking towards the tail of the other, and having the 

 right edges of their bodies in close apposition. When examined 

 twenty-fours later neither had spawned, but two hours after this 

 one had spawned, and the other was in the act of spawning. The 

 spawn was seen to issue very slowly from the dilated vagina, and 

 the animal very gradually shifted its position to permit the spawn 

 to assume a ribbon-form, and cause it to adhere by one of its 



* In naming these animals I have followed Messrs. Alder and Hancock 

 in their ' Synopsis of British Nudibranchiate Mollusca,' in their beautiful 

 monograph published by the Ray Society in 1845. These gentlemen con- 

 sider the Goniodoris Barvicensis to be a variety of Goniodoris nodosa. 



Ann, ^ Mag. N, Hist. VolxVii, 2D 



