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 : 



CyPEis, genus 



Can DONA, genus 

 Cyprideis, sub-gen. ? 



Cypkidea, sub-gen. ? 

 Cythere, genus 



Cythebeis, sub-gen. 



Carapace-valves. 



Shape. 



Contact- 

 margins. 



Thin. ; Ovate or oblong. 



Thin. 

 Thickish. 



Thick. 

 Thickish. 



Thick. 



Long-ovate or 

 oblong. 



\ Oblong. j 



Ovate. 

 Oblong. 



Oblong. 



Cytheridea, sub-gen. .'Thickish 



Cytherideis, sub-gen. Thin. 

 Bairdia, sub-gen. . Thin. 



Cytherella, sub-gen. 1 



Triangular or 

 ovate-oblons;. 



Triangular. 

 Thick. Ovate or oblong. 



w 



5 a- <i 



2 ro ° 

 o,- c, !4? 



^ ° re' 

 =! S - 



a •— ?= 



-PS 

 P 3 !=^ 



i-ll 



•rris. J 



Larger than Cxji 



Notched at the 



antero-ventral 



angle. 



Peach-stone-shaped. -1 



Often showing one [ 



central and two f 



posterior tubercles.-' 



The three tubercles 



strongly shown ; 

 the postero-ventral 

 one developed into a 

 long ventral ridge 



Hinge-margins. 



■J !rt 



I Grooved ' 

 I and 

 Ifurrowed., 



Simple, inclined 

 to be sulcate. 



Knurled. 



Hinge consisting of 

 bar and furrow, 

 with terminal teeth. 



Hinge consisting of 

 terminal teeth ; bar 

 and furrowobsolete, 



Knurled. 



Simple and sulcate, 

 as in Cypris. 

 Quite simple. 



No special hinge. 



Suh-family — Cyprin^, Dana. {Ci/jmdida', Baird.) 



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

 the Tertiary CyprhicB 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 Notodrovias, 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. 



