OSTRACODA NEW TO BRITAIN. 109 
Lastly, I have myself found it in extraordinary numbers in 
estuarine pools at Warkworth. 
The following table indicates the Crustacea with which C. to- 
rosa was found associated in the localities above specified :— 


Sedgefield. Gravesend. Hartlepool. Warkworth. 
(fresh water) (brackish). (brackish). (brackish). 
Cypris ovum. Crangon vulgaris. | Palzemon varians. | Crangon vulgaris. 
—— gibba. Cypris gibba, Gammarus locusta, 
cuneata. aculeata. 
Candona serrata. | Candona lucens. 
reptans. 

The animal of C. torosa differs only very slightly from that of 
the genus Cythere. The limbs (except the first pair of legs, of 
which, owing to their minute size, I have not been able to obtain a 
satisfactory drawing) are represented in Pl. III. figs. 11-15. The 
only characters by which I can distinguish them from the limbs 
of Cythere are the absence, from the second joint of the inferior 
antenna, of the long stout seta which is always found in that 
genus, and the presence, on the coxe of the last pair of legs, of 
four or five rows of long hairs having apparently a semiverticillate 
arrangement. The tufts of bristles which occur in other situa- 
tions are similar in disposition to those of Cythere. Some of the 
longer sete or hairs are terminated with a peculiar ringed and 
serrated armature, which is shown at fig. 15. This character is 
always confined to certain hairs, which are constant in position, 
and is found likewise in Cythere. I have not been able, in my 
recent specimens of C. torosa, to detect the regular tuberculation 
figured and described by Mr. Jones; but there is much difference 
in the various specimens, according to age and locality, and it is 
evident that considerable latitude must be allowed in this as well 
as in the spinous armature of the carapace. In comparatively 
few of the Gravesend specimens have I found any appearance of 
the single spine, while in those from Warkworth it is almost 
constant. I have frequently, in examining C. torosa, found the 
carapace almost filled posteriorly with a very large mass of ova. 
This fully accounts for the prodigious quantities in which the 
