CR USTA CEA—OSTRA CODA . 



363 



103. E. waldronensis Ulrich. (Fig. 1668, 7n, n.) Siluric. 

 Sulcus narrow, long, nearly straight, with a small tubercle in 



front of sulcus; slightly inore elongate than preceding. 

 Waldron (Niagaran) shales of Indiana. 



104. E. rhomboidalis Jones. (Fig. 1667, f,«.) Devonic. 

 Form subrhomboidal, somewhat oblique ; sulcus short and 



broader than in other species ; surface with fine inosculating longi- 

 tudinal striae. 



Hamilton of New York. 



XLII. Cypridina Milne-Edwards. 

 Shell generally acuminate, oviform, rarely somewhat oblong; 

 anterodorsal edge projecting beak-like over the strongly defined 

 notch ; muscle spot large, subcentral, often visible on the exterior. 



Fig. 1667. a-c, Krausella arcuata (lOl), right valve, X 1° 5 ^-/> Bairdia legu- 

 viinoides (io8), right ventral and anterior views, X ^4 > g~^i B- cestriensis (109), 

 left right and dorsal views, X '^Wj'ij'^ ^f Pontocypris {^?^ acuminata (m), left 

 valve, X 10 ; /, l\ m, «, Bythocypris (P) robusta (112), left, posterior dorsal and 

 right views, X lo ; ^-^> Bairdia devonica (107), ventral, right and posterior views, 

 X 10 ; r, s, Entomis madisonenns (102) ; /, u, E. rhoi7iboidalis (104), right valve, 

 X 16; V, XV, Cypridina Aerzeri (lo^), left valve, X ^^J -^^ J' ^- ^^^-bovata (106), 

 left^valve, X 3- (After Ulrich and Jones (/, m).) 



Numerous living forms in the Pacific and Indian oceans and in 

 the Mediterranean ; fossil from the Ordovicic to the Eocenic, par- 

 ticularly in the Carbonic. 



