THE ANNALS 
AND 
MAGAZINE OF NATURAL HISTORY. 
No. 114. JUNE 1846. 
XLVII.—On the Development of the Ova of the Nudibranchiate 
Mollusca. By Joun Retp, M.D., Fellow of the Royal College 
of Physicians of Edinburgh, and Professor of Anatomy and 
Medieime in the University of St. Andrews. 
[With a Plate.] 
Tue following observations upon the development of the Nudi- 
branchiate Mollusca were made on the ova of the Doris bilamel- 
lata, Doris tuberculata, Goniodoris Barvicensis, Polycera quadri- 
lineata, Dendronotus arborescens, Doto coronata*, and a species 
of Holis having numerous flattened papille, 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. Hight 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 Geniodoris nodosa. 
Amn. & Mag. N. Hist. Vol. xvii. 
