19 



Head rounded in front, eyes small, in the temples, 

 very remote. 



Abdomen with from 9 to 10 articulations, trilobate. 

 Tail expanded as large as the head.* 



Genus Ninth. AMPYX. 



Body very short, contractile. 



J3uckler large, triangular, gibbous; eyes not re- 

 markable. 



Jlbdomen short, articulations few (6 ?), trilobate. 



Tail expanded, not so large as the head. 



Professor Dalman has two other genera, which he 

 calls Olenus and Battus, the first is the Paradoxides, 

 and the second the Agnostus of Brongniart. 



In the 8th Volume of Annales des Sciences Natu- 

 relles there is a highly valuable paper " Sur les Tri- 

 lobites et leurs gisemens," by the Count Rasoumow- 

 sky, in which he describes some new trilobites from 

 Russia; the one which he has figured and described 

 as a Calymenef from Tzarsko-Selo, undoubtedly be- 

 longs to a new genus, very near to the Isotelus. The 

 middle lobe is visible or naked through its whole ex- 

 tent, and the lateral lobes near the tail are covered 

 with a thick cuticular membrane. This genus we 

 propose to call Hemicrupturus, and may be thus cha- 

 racterized. 



* Some of the species described by Professor Dalman as in- 

 cluded in this genus, we think ought to be referred to that of the 

 Isotelus. 



t The editors of the Annales remark that this is not a Caly- 

 mene. but that it appears to belong to the genus Asaphus. 



