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DESCRIPTION OF A NEW TRILOBITE FROM NOVA SCOTIA, 

 By Jacob Green, M. D. Prof. Chem. in Jef. Med. Col. Philada. 

 ASAPHUS 1 CRYPTURUS. Green. 



Cauda acuta ; articulis terminalibus ohscuris ; parte mar- 

 ginal! vix membranacea ; corpore convexo. 



A tolerably perfect fragment of the abdomen and 

 tail of this highly interesting fossil, comprised all of the 

 animal which has yet been found. Eleven articulations 

 of the middle lobe, and ten of the lateral lobes are quite 

 distinct. All the costal arches or ribs are smooth and 

 rounded, being without pustulatious striae or grooves. 

 Four of the upper arches of the dorsal, or middle lobe, 

 are longer than those on the sides of the body, a pecu- 

 liarity which is sufficiently decisive to mark the species. 

 Indeed this organization furnishes a striking exception 

 to the generic characters of the Asaphus, as given by 

 Professor Brongniart, who states "that the middle lobe 

 of the abdomen is rarely more than one-fifth the width 

 of the body." But what is more remarkable, and still 

 further distinguishes this animal remain from all other 

 Asaphs, is the epidermal covering which concealed the 

 terminal articulations of the tail. In our specimen 

 there is no appearance of what has been called the mem- 

 braneous development beyond the lobes of the animal, 

 another circumstance which seems to separate it from 

 the genus Asaphus. The body is quite convex, and 



