ARTICULATA. 



[421, Cast]. Harpes ungula, Barrande. 



Head. From the Upper Silurian Limestone at 

 Kronieprus, Bohemia. In this genus the head, which 

 occupies more than a third in length of the whole ani- 

 mal, is surrounded by a broad, flat margin, which is 

 pioduced posteriorly nearly to the extreme end of the 

 body. The body-segments and tail are usually wanting, 

 as is the case in this specimen. Original in the Ward 

 Collection of the University of Rochester. 



No. 159. [423, Cast]. Homalonotus delphinocephalus, Murch. 



This genus is so named because the three-lobed 

 aspect, so characteristic of the family, is, in a great 

 measure obliterated, and the back appears smooth and 

 uniform. The cephalic and caudal shields are hyper- 

 bolic; the rings number thirteen. This species is char- 

 acterized by the distinct trilobation of the tail in all its 

 stages of growth, as well as by its slender body and 

 acute caudal extremity. The specimen is from the 

 Upper Silurian at Dudley, England. 



Size, 7x4. 



No. 160. [426, Cast]. Ulaenus giganteus, Brong. 



The general form of this species is variable, from its contractility. It has 

 ten articulations; prominent eyes, and large, convex buckler and caudal shield. 

 This specimen is from the Lower Silurian, Angers, France, and is in the Ward 

 Collection of the University of Rochester. 



No. 161. [428, Cast]. Lichas Boltoni, Green. 



This beautiful Trilobite is easily recognized 

 by its peculiar scabrous surface, depressed 

 body and head, and the free extremities of the 

 segments pointing backwards. The thorax is 

 large and is divided into eleven segments. It 

 is from the Niagara Group (Upper Silurian), 

 Lockport, N. Y., where it is a characteristic 

 fossil, although not often found entire. 



Size, 7x6. 



