10 



THE ENTOMOSTRACA OF 



For the purposes of the palaeontologist a succinct table of the characters of the 

 carapace of the chief forms of the Ostracoda will be useful : 





Carapace-valves. 



• 





Contact- 



N 







Shape. 



margins. 





Hinge-margins. 



Cypris, genus 



Thin. 



Ovate or oblong. 



W 



' • • ■) 



Simple, inclined 



Can dona, genus 



Thin. 



Long-ovate or 

 oblong. 



** CD JH 



►w o *^ 



Larger than Cypris. J 



to be sulcate. 



Cyprideis, sub-gen. 1 . 



Thickish. 



-) r 



S^ o 





Knurled. 







[ Oblong. i 



* p-Bj 



Notched at the 





Cypridea, sub-gen. ? . 



Thick. 



) I 





antero-ventral 

 angle. 



? 



Cythere, genus 



Thickish. 



f Ovate. 

 ( Oblong. 



;, and lined 

 w laminar pi 

 ona, and JB«< 



Peach-stone-shaped . -\ 

 Often showing one I 



central and two 

 posterior tubercles.-' 



Hinge consisting of 

 bar and furrow, 

 with terminal teeth. 









The three tubercles 1 











S&i 



strongly shown ; 



Hinge consisting of 



Cythereis, sub-gen. 



Thick. 



Oblong. 



S' 1 " ^- 



the postero-ventral ) 



terminal teeth ; bar 









' S-* 



one developed into a 



and furrow obsolete. 









g-'l 



long ventral ridge. J 





Cytheiudea, sub-gen. . 



Thickish. 



1 Triangular or J 



en 





Knurled. 



jCytherideis, sub-gen. 



Thin. 



| ovate-oblong, "j 



p * 



OQ p— 



. . . .{ 



Simple and sulcate, 

 as in Cypris. 



Bairdia, sub-gen. 



Thin, j 



Triangular. J 



C-* GO 



v 



Quite simple. 







{ 

 Ovate or oblong. ., 



1 



Grooved ) 



and 

 'urrowed.J 





Cytherella, sub-gen. ? 



Thick. 



No special hinge. 





' 





Sub-family — Cy prince, Dana. {Cypridida, Baird.) 



I have alluded to the difficulties in the way of the palaeontologist when comparing 

 the Tertiary Cyprince with their existing representatives ; and in the following descrip- 

 tions I shall not dwell on the probabilities of the agreement of any of our few fossil 

 forms with the carapaces of Cypria, Cyprois, and Notodromas, but arrange them in 

 two groups accordingly as the carapaces more or less resemble those of the known 

 recent species of the genera Cypris and Candona. 



At the same time it will be advisable to point out the anatomical characteristics of 

 all the above-mentioned divisions, that the subject may be fairly presented in its 

 zoological aspect. 



