18 



bercles on the buckler not reticulated; by the abdo- 

 men with but 8 articulations. 



From Jlsaphm. By the middle lobe, which is double 

 the size of the lateral ones; by the absence of a mem- 

 branaceous expansion on the sides; by the non-reticu- 

 lation of the eyes, Sec. 



From Ogygia. By the rolled form, the rounded 

 posterior angles of the buckler, and the distinct arti- 

 culation of the longitudinal lobes. 



From Paradoxide and tfgnoste by characters too 

 obvious to be enumerated. (See Annals of N. York 

 Lyceum, Sec. Vol. I. pp. 174-5.) 



In 1826, J. W. Dalman published in the Transac- 

 tions of the Swedish Academy, and also in a separate 

 work, an account of the trilobites found in the North 

 of Europe, in which he has enriched the family by a 

 number of fine species, and with the following genera, 

 which he modestly proposes merely as subdivisions. 



Genus Seventh. NILEUS. 



Body short, capable of contraction into a sphere, 

 smooth, convex. 



Mdomen with about 8 articulations, without any 

 dorsal longitudinal furrows. 



Buckler sub-lunate, with large lateral eyes. 



Tail expanded, not so large as the buckler, without 

 lobes. 



Genus Eighth. ILLJENUS. 

 Body ovate oblong, contractile. 



