180 Dr Hissert on the Limestone of Burdiehouse 
from any other circumstance, to infer that certain of the minute 
animals thus described are referable to the Cypris, the prosecution 
of this research cannot be more safely conducted than in still 
confining our attention to the recent family of the Cypridea, for 
the detection, if possible, of other forms belonging to animals pre- 
sumed to be of common habits. Another form, for instance, rather 
approaches to that of the Daphnia than the Cypris. But if, in- 
stead of an external crust, we could arrive at the knowledge of 
an internal organization, it is not improbable that the entomos- 
traca thus compared might prove to be different animals altoge- 
ther. 
It is for this reason that I would name the animal repre- 
— sented in the three different views of the annex- 
* ed wood-cut. by the cautious name of Daphnoidia 
A ‘ © rather than Daphnia ; indicative of an individual 
approaching to the recent Daphnia. 
The shell of the Daphnia, like that of the Daphnoidia of 
Burdiehouse, is not described as exactly bivalve, but as subuni- 
valve, opening longitudinally on one side only of the encased 
animal. This character may, I think, be plainly detected in the 
instance of the fossil example. I shall not venture upon assign- 
ing to it a specific name, until I am better assured with regard 
to its proper generic character. 
Other minute animals possess shells of extreme tenuity, too 
many of which appear in a crushed and broken state. In this 
form they exhibit a sort of spiral organization by no means unlike 
that of the Planorbis or Spirorbis, to which they were referred 
by an eminent conchologist, whose opmion regarding them I 
consulted. But, upon a renewed examination of certain of these 
remains, which, owing to an infiltration of calcareous matter, 
have had their forms tolerably well preserved, I am now inclined 
to place some doubt upon the judgment which had been passed 
upon their character. 
The external form of one animal most resembles that of the 
