73 



little from those above noticed, these are also with- 

 out names. Under such circumstances, we have 

 thought it expedient to group these relics under 

 the generic term of Cryptolithus, a name analogous 

 to Calymene, Asaphus, Ogygia, and Agnostus, and 

 which may with propriety be applied to the animal, 

 should it ever be discovered entire.* 



Body, contractile. 



Buckler, lunate, convex, outer edge surrounded by 

 a semicircular, reticulated, or tessellated border. 



Front or middle lobe of the buckler very protube- 

 rant. 



Oculiferous protuberances, none. 



Abdomen, much compressed, trilobate. 



CRYPTOLITHUS TESSELLATUS. Green. Cast No. 28, 

 and Fig. 4. 



Clypeo rotundato, fronte valde convexo, capite an- 

 tice semicircular! margine tessellato ornato. 



Outline of the buckler hemispherical, the edge sur- 

 rounded by a semicircular border of tessellated or 

 rounded punctures, in three concentric rows in front 

 on each side near the posterior angle of the buck- 

 ler, these rows of punctures are more numerous^ 

 the front is highly convex; is rounded before, and 



* Since the above was written, and the C. Tessellatus pub- 

 lished, I have received a fine specimen of this trilobite from Pro- 

 fessor Eaton, in an almost perfect state, so that the entire ani- 

 mal can now be described. 



G 



