CRUSTACEA. 



87 



No. 163. [431, Cast]. Lichas pustuloSUS, Hall. 



Pygidium. From the Lower Hekler- 

 berg (Upper Silurian), Schoharie Couuty, 

 N. Y. 



No. 163. [437, Cast]. Paradoxides Bohemicus, Bock. 



This genus is distinguished by a broad, club-shaped 

 glabella, large head-spines, oblong eyes, from sixteen 

 to twenty flat body-rings, and a very small pygidium. 

 It includes some of the largest Trilobites known, which, 

 to the number of about twenty species, characterize the 

 Lower Silurian formation of Bohemia, Sweden and 

 England. From the Lower Silurian at Ginetz, Bo- 

 hemia. Size, 6x3. 



No. 164. Pliacops bufo (Var. rana.). Green. 



Head and Tail. Trilobites of the genus Phacops have 

 very large, prominent, granulated eyes, forming a segment 

 of a cone, distinct trilobation, and eleven body-rings. 

 This species, the Calymene macropthalma of Brongniart, 

 and perhaps identical also with the Phacops latifrons of 

 Bronn, has a very convex head, occupying one-third of the 

 whole length, a tuberculated glabella, and the eleven pleurae 

 bent down at the extremities. There are 66 lenses in each 

 eye. These specimens are from the Hamilton Group (Devonian), Otisco, N. Y. 



No. 165. [445, Cast]. Proetus longicaudns, Hall. 



In this genus, the eyes are of a moderate size, very 

 prominent, smooth, and joined rather closely to the 

 glabella; and the body has ten segments. This speci- 

 men (coiled) is from the Hamilton Group (Devonian), 

 Iowa. 



