322 PROCEEDINGS OF THE NATIONAL MUSI-JIM. vol. xxxv. 



Beginning with the most simple type, the genera may be defined 

 briefly as follows: 



Genus KIRKBY1NA, new. 



Beyrichiella f Jones and Kirkby, Ann. and Mag. Nat. Hist. (5), XVIII, 

 1SS6, p. 260. 



Carapace small, less than 1 mm. in length, rather short, subovate to 

 subquadrate, ventricose, thickest anteriorly, with a simple primitian 

 sulcus about the middle of the dorsal half. Valves unequal, the right 

 slightly larger and overlapping the edges of the left. 



Genotype. — Kirhbyina reticosa {Beyrichiella f reticosa Jones and 

 Kirkby). 



In the same paper a Jones and Kirkby describe a second more tumid 

 species, likewise referring it doubtfully to Beyrichiella under the name 

 B. f ventricornis. At present only these two British species may be 

 safely placed in the genus Kirhbyina. There are a few as yet un- 

 studied, Primitia-like Ostracoda in American deposits of Carbon- 

 iferous age that may turn out to belong here. 



Kirhbyina resembles Primitia, but is readily distinguished by its 

 overlapping valves and thicker anterior end. In Primitia it is the 

 posterior half that is usually the thicker. Beyrichiella has a more 

 elongate shell and broader sulcus, while its left valve and not the right 

 is the larger. 



Genus BEYRICHIELLA Jones and Kirkby. 



Beyrichiella Jones and Kirkby, Geol. Mag., Dec. 3, III, 1886, p. 438: Proc. 

 Geo!. Assoc, IX, 1886, p. 506. 



Beyrichiella (part) Ulbich and Bassler. Proc. U. S. Nat. Mus., XXX, 1906, 

 pp. 151-155. 



Syria plic Jones and Kirkby, Trans. Royal Dublin Soc. (2), VI, 1896, ]». 190. 

 Ulbich and Bassler, Proc. U. S. Nat. Mus.. XXX. 1006. p. 152. 



Kirkhyia Cossmann, Revue Critique de Paleozoologie, III, 1809, p. 45 (pro- 

 posed for Sijnaplie, preoccupied). 



Carapace small, 1 mm. or less in length, elongate subquadrate, 

 thickest anteriorly, with a rather broad median sulcus giving the shell 

 a bilobed aspect ; a low, transverse ridge in the ventral part cuts off 

 the sulcus and unites the lower parts of the two lobes. Valves un- 

 equal, the edge of the smaller right valve being set into the over- 

 lapping ventral and end parts of the larger left valve. 



Genotype. — Beyrichiella cristata Jones and Kirkby. 



The writers fail to see more than specific differences between B. 

 cristata and Kirhbya annectens, the type of Synaphe Jones and 

 Kirkby (not Synaphe Huebner). It is, therefore, placed here as a 



"Ann. and Mag. Nat. Hist. (5), XVIII, 1886, p. 260. 



