6 



pygidium, we can not say with certainty that this form 

 helonga to Zethus." Burmeister rekvs the Z. verrucosus 

 to C. Tristani ; Buch, to C. Bhimenbachii, and Doctor 

 Volborth, in the Trans. Royal Mineral So., St. Petersb., 

 1847, quotes the Z. uniplicatus, Pander, under the genus 

 Cheirurus and Z. verrucosus, Pander, under Loven's ge- 

 us Cybele. Corda takes the same species for the type of 

 his genus Atractopyge. Nieszkowski assigns the Zethus 

 uniplicatus to the genus Sphcerexochus. Portlock (page 

 289) refers the genus Zethus to Amphion. It is sufficient- 

 ly evident that the generic desci'iption is very imperfect 

 and ill defined ; and also that its type belongs to the 

 genus ^eraurus, Green, or to its sub-genus, /Sphcerexoch- 

 us ; and that all attempts made by authors to class as its 

 type the second species, Zethus verrucosus, with Pander's 

 uncertain description, has only propagated an error that 

 leads to great confusion. 



In the Petrifactions of the Duchy of Brandenburg? 

 published in 1834, Klceden, p. 106, gives a short descrip- 

 tion of Calymene punctata, without figures. 



Buckland, in the Bridgewater Treatises, 1836, on pi. 

 xlvi, fig. 6, represents the Crypt, punctatus as Asaphus 

 tuberculatus. The specimen was cited from Dudley 

 and from Mr. Johnson's collection. It is evidently the 

 same that Brongniart figured on pi. i, fig. 3a. 



In 1839, Murchison in The Silurian System, on plate 

 xxiii, fig. 8, represents the C. punctata, and on pi. xiv, 

 fig. 1, the C. variolaris. The last figure has 13 segments 

 in the thorax. Fletcher remarks, in his article on the 

 Dudley Trilobites : "A recent inspection of the specimen, 

 figured by Sir R. I. Murchison (pi. xiv, fig. 1) fronij 



We may be justified in rejecting Zethus of Pander, a name lately revived by 

 Dr. Volborth, for the genus as constituted by Pander, consisting of the fol- 

 lowing species ■. Zethus uniplicatus and Z. verrucosus ; to either of which the 

 meagre and incorrect description will apply. The firSt of these being, by Dr. 

 Volborth'e own admission, a species of Cheirurus, the second a Oybele. He 



