344 POURTALKSIA. 



SPATANGIDAE. 



Family Spatangidae Agass. 1841. Prod. Mon. Rail, (emend.) 



ANANCHYTIDAE. 



Subfamily Ananchytidae Alb. GrA8, 1S48. ficli. fuss. Iser. 



This subfamily includes Spatangoids having ambulacra flush with the sur- 

 face of the test, the apical system more or less elongate, but not discon- 

 nected. The anterior groove disappears in some genera, as in Cassiduloids. 

 The discovery of the genera Neolampas and Hoinolampas, where we find 

 the spatangoid structure of the actinostome, as well as that of the form 

 without bourrelets but with phyllodes, shows that the Ananchytidae are 

 not as disconnected a group among Spatangoids as we have been led to 

 suppose thus far, the genus Neolampas showing the possibility of finding Cas- 

 siduloids without the bare bands of the actinal surface, yet having the simple 

 pores of the Ananchytidae and the peculiar structure of the mouth of the 

 Cassidulidae, though not showing the faintest tendency to the development of 

 plastrons so characteristic of the other Spatangoids. 



POURTALESIA. 



Pourtalesia A. Ac ass. 1869. Bull. M. C Z., I. p. 272. 



This genus is the living representative of Infulaster of the cretaceous 

 period, holding the same relation to it which Hlmiehopygus. with its pro- 

 jection covering the anus, holds to Echinolampas, if the posterior part of 

 the test of the former were drawn out into a long spout. The outline of this 

 genus, as well as of Infulaster, is very peculiar, and at first sight no one 

 would take for a Sea-urchin the elongate, bottle-shaped body with its thin 

 and transparent test. It is more like a Holothurian ; the anus is at one ex- 

 tremity suprainarginal, while the mouth is placed at the other. The short, 

 vertical diameter, as compared to its length ; the absence of any feature 

 which would indicate the presence of a petaloid ambulacra] rosette ; the 

 long, slender, curved spines, far apart, supported upon peculiar tubercles, 

 mark this genus as one of the most interesting brought to light by 



