a * 
84 
The name of this eels is derived from the remark- 
able spinous projections from the caudal end; this” 
peculiar organization separates it widely from the 
other genera. The Paradoxides Spinulosus of Wah- 
lenberg, which is supposed to be the old Entemolithus 
Paradoxus of Linné, the fossil, with which all the tri- 
lobites were for a long time confounded, has not 
only projecting spines from the tail, but See all the 
costal arches of the lateral lobes. The presence of 
eyes or of oculiferous tubercles in the Ceraurus, would 
alone be sufficient to separate it from the genus to 
which that interesting fossil belongs. In the eighth 
volume of Annales a Sciences Naturelles, Count 
Rasoumowsky has figured and described the frag- 
ment of a very curious relic, which seems to be an 
intermediate link between our genus and paradox- 
ides; in addition to a number of filamentous elonga- 
tions of the costal arches, a curved spine seems to 
project from the end of the tail, as in the 4. limulurus. 
No name is given to this trilobite, which appears to 
have been found on the banks of the Yaousa, near ” 
Moscow, where it occurs in black, coarse, argillaceous 
schistus. The Ceraurus is probably a very rare ani- ; 
mal remain, as we have only met with it, inthe unri- — 
valled cabinet of trilobites belonging to the Allenna | 
Institute. 
CERAURUS PLEUREXANTHEMUS. Green. Cast No. 33. — 
Fig. 10. ANT NS 
Clypeo postice arcuato, angulo externo in mucro- © 
nem valde producto; oculis minimis remotis, post- 
ve 
