272 BULLETIN OF THE 



Pourtalesia miranda A. Ac, nov. gen. et sp. 



A single specimen of this interesting genus was dredged at a depth of 

 349 fathoms. It is a living representative of Infulaster of the cretaceous 

 period, holding the same relation to it which llhynehopygus, with its projec- 

 tion 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, and of Infulaster, is very peculiar, and at first sight no one would 

 take for a -Sea-urchin the elongated, bottle-shaped body with its thin and 

 transparent test. It is more like a Holothurian ; the anus is nearly at one 

 extremity, 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 ambulacral rosette ; the long, 

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

 this genus as one of the most interesting which have been brought to light 

 by Mr. Pou^tales. It forms a valuable link in our appreciation of the affin- 

 ities of Spatangoids proper with Spatangoids in which the mouth is not 

 labiate. Seen from above, the outline is bottle-shaped, the neck being the 

 posterior extremity. At the base of the neck the test carries a deep pit, 

 surmounted at its anterior extremity by a rostrum projecting from the 

 test, and under this, at the bottom of the pit, is placed the anus. Seen in 

 profile, the anterior extremity is almost vertically cut off", the test arching 

 regularly from the apical system to the rostrum, where it is abruptly cut off, 

 forming a regular curve to the posterior extremity, which extends beyond 

 the anal system like a snout thickened at the end, surmounted at its 

 extremity by an accumulation of minute deep violet-colored tubercles, 

 which carry no spines. The lower surface is convex, regularly arched from 

 the posterior to the anterior extremity. The posterior pair of ambulacra 

 extend on both sides of an elongated plastron to the base of the snout-like 

 prolongation, where they curve sharply upwards, and follow close to the 

 abactinal part of the test, along a marked wedge-shaped ridge, extending 

 from the apical system into the rostrum, protecting the anus, to the apical 

 system, situated almost at the summit of the nearly vertical anterior ex- 

 tremity. The pair of anterior ambulacra take a similar course, but curve 

 more regularly, and do not extend beyond the median line towards the 

 posterior end. The odd ambulacrum is made up of two lines of pores far 

 apart, situated in the deep anterior groove. The abactinal system consist- 

 ing of four large genital openings, placed close together, with the mad- 

 reporic body tolerably well defined in the centre, is situated at the origin 

 of the anterior groove, this is flanked by prominent ridges extending 

 from the apical system, gradually disappearing towards the mouth, placed 

 at the other extremity of the anterior groove, which increases in depth on 



