In 1830, Pander published his Beitrsege zur Geogno- 

 sie des Russlands. In his review of the heterogeneous 

 species, which then existed under the genus Cahjmene 

 of Brongniart, he saw the confusion caused by its ill de- 

 fined limits, and properly sub-divided the genus in 

 proposing the genera Amphion aud Zethus ; but not 

 having in his possession the type of the genus, {Caly- 

 mene Blumenbachii) he has added to the confusion in 

 the nomenclature. He thus describes his genus Zethus: 

 "Middle body (thorax) as in the geaus Calymene, {Pha- 

 cops and Amphion) side segments of the body and tail 

 provided with strong folds, the latter apjieariug to be free 

 at their extremities. We count 16 segments of the body 

 and tail together, for we are unable to properly sepa- 

 rate them from each other. Cheeks without furrows ; no 

 eye tubercles." Pander refers two species to this genus, 

 the type Z. uniplicatus (pi. v, fig. 7,) and Z. verrucosus 

 (pi. V, fig. 6, also i^l. iv, fig. 4). 



Portlock says : "The two species which Pander cites 

 as examples of this genus, do not agree with each other 

 in what must be considered an essential character." The 

 author of the genus ZeUui^ remarks, with regard to Zethus 

 verrucosus : "We are only in possession of a part, and 

 it may be possible that the fossil belongs to the Ento- 

 mostracites pxmctatus, Wahl., the Calymene punctata, 

 Dalman ; but we see from the fragment, more or less 

 disarranged and broken, that the segments^and also the 

 head shield were covered with close layers of tubercles, 

 while those of C. punctatus appear to be smooth. The 

 furrows of the glabella can be seen, as in Amphion fron-- 

 talis ; eyes wanting. Not having in our possession the 



