no. 1646. REVISION OF BEYRICHIIDsE— ULRICH AND BASSLER. $H 



SILURIAN SPECIES, 



Gtenobolbina auricularis (Bollia auricularis .Times). 



DEVONIAN SPECIES. 



CtenobolMna minima " Ulrich. 



MISSISSIPPIAN SPECIES. 



CtenobolMna loculata a Ulrich. 

 Krause B and Steusloff c have described and referred a number of 

 unisulcate Ordovician species to Entomis. This arrangement of the 



species is probably incorrect, the present writers doubting- even that 

 the typical Entomidse are Ostracoda at all. Krause's and Steusloff's 

 cntomids, on the contrary, seem to be closely allied to Gtenobolbina, 

 and, in part at least, congeneric with species referred to this genus. 

 Others like Krause's E. sigma and E. obliqua are so completely bi- 

 lobed as to suggest DilobeUa. Pending an opportunity to study speci- 

 mens of all these species, those not elsewhere referred in this work 

 may be provisionally left where their authors placed them. 



As stated on page 200, Ctenobolb'tna tumida Ulrich'' (see fig. 24, 

 p. 292) is now thought to be a peculiar Beyrichia and to have no very 

 intimate relations to the typical species of Gtenobolbina. Indeed, 

 the bulbous end of the carapace in B. tumida is regarded as anterior, 

 whereas in ('. ciliata the thicker end is posterior. Hence, if the spe- 

 cies is allied to Gtenobolbina at all. it must be to the ('. subcrassa 

 section and not to the typical section of the genus. 



The genetic alliance of Gtenobolbina to Beyrichia (more especially 

 to the subgenus Steusloffia) has been discussed on pages 296 to ■_ , l> < .». 



Genus DREPANELLA Ulrich. 



Depranella Ulrich. Jour. Cincinnati See. Nat. Hist., XIII. 1890, pp. 



117, US. 

 Depranella Miller, North Anier. Geol. and Pal., First App., 1892, p. TUT. 

 Drepanella (part) Ulrich, Geol. and Nat. Hist. Surv. Minnesota. Final 



Rept., III. Pt. 2, 1894, ]». 670. 



Carapace equivalves, usually about 2.5 mm. long, compressed con- 

 vex, somewhat oblong, subquadrate to subelliptical in outline; dorsal 

 edge straight, ventral side gently convex, ends subequal, the post- 

 dorsal angle sharper than the anterior. A constant sickle-shaped, 

 sharply defined ridge runs nearly parallel with and generally not far 

 within the posterior and ventral edges of the valve-. Central and 



" American species. 



''/cits. d. d. geol. Gesell., XLIV, 1892, pp. 383-399; XLVITI, 1896, p. 935. 



c Idem, XLYI, 1894, p. TTT. 



<* Jour. Cincinnati Soc. Nat. Hist., XIII, 1890, p. Ill, pi. vii, figs. .".</. 5&. 



