502 MONOGRAPH OF THE ECHINODERMATA. 



Goniopygvs, Agas. 



Differs from Salenia in the absence of the superanal plate ; 

 and the ovarial plates are not united throughout their length 

 to the interovarial, from which it results that the oviductal 

 apparatus constantly presents a decagonal rosette ; * the in- 

 terambulacral areae are much less tubercular than in the other 

 genera of this family ; the coronal plates in the upper part of 

 the shell often bear only a single large tubercle ; a character 

 peculiar to this genus is the absence of the radiating grooves 

 on the tubercles of the interambulacral areae. 



Peltastes, Agas. 



The altogether peculiar form of the oviductal apparatus 

 (resembling a shield) in several species, has induced the au- 

 thor to raise them to the dignity of a genus. The ovarial plates 

 extend over a considerable portion of the interambulacral 

 areae, surrounded on each side by the interovarial plates, to 

 which they are united throughout their whole length, so that 

 instead of a star of ten rays, there is only a single pentagonal 

 rosette. 



Goniophorus, Agas. 



This genus is very closely allied to Salenia, but distin- 

 guished from it, as well as from the two preceding genera, by 

 the peculiar structure of the oviductal plate, the surface of 

 which is covered with rigid and salient ridges, which are not 

 sutures, the latter being scarcely visible to the naked eye ; 

 besides the interovarial and ovarial plates there is a large su- 

 peranal plate, which, placed (as in Peltastes and the second 

 division of Salenia) between the anterior ovarials and the 

 anal aperture, pushes away the latter backwards ; the form 

 of the whole apparatus is that of a pentagon, whose salient 

 angles are formed by the interovarial plates. 



The plates of this the first part are neatly executed, and 

 the more important characters illustrated by magnified views. 

 In calling the attention of naturalists to this Monograph, we 

 think but one opinion can be entertained as to its value in 

 relation to the sciences of Geology and Zoology ; and we 

 most sincerely trust that success will attend the labours of 

 its author, whose intimate acquaintance with the subject pe- 

 culiarly qualifies him for undertaking the elucidation of one 

 of the most interesting groups in the whole animal kingdom. 



1 One of the principal characters of Goniopygus appears to he the central 

 anal opening, which is sometimes circular, sometimes angular, according 

 to the species. 



