80 S. LOVEN, ON POURTALESIA, A GENUS OF ECHISOIDEA. 



The falycinal system of the Pourtalesiadaj is rnuch more anomalous, and at tlio 

 same tijae not a little unscttled. In the specimen of Pourtalesia Jeffreysi, Pl. I,fig- /, 

 the calycinal system is brought out of contact with the interradia 1 and 4 throuoli 

 the interjacence of the detached plates of 5. Its general form is that of an irregular 

 pentagon. Its constituents are all coalesced into one piece, the madreporal filter spread- 

 ing its pores över its central forepart. The radials are not to be distinguished. The 

 four sexual apertures are displaced, not answering to tlieir respective interradia, raoved 

 for^vard, those of 2 and 3 being near the ambulacrum III, and those of 1 and 4 almost 

 opposite the II and IV. Another specimen, PL V, fig. 27, 2&\ 29, not very different 

 from the first, has the madreporic filter occupying the hinder part of the central space, 

 the anterior pair of sexual pores nearly answering to the interradials 2 and 3, the 

 posterior being pressed forward so as to front the ambulacra II and IV. An impres- 

 sion, not unlike an orbit, near the end of ambulacrum III, fig. 2,9, possibly indicates 

 the existence of a radial. In a third specimen. Pl. V, jig. 25, 26, the disordered con- 

 dition of the system is still raore obvious. The costals 1 and 4, separated from the 

 rest by distinct sutures, adjoin the ambulacra II and IV, and are driven widely apart 

 by an advanced plate of 5. 



In Pourtalesia laguncula, Pl. VII, jig. 52, much the same holds good. There are 

 no ti'accs of radials. The costals 1 and 4, bounded by distinct sutures, adjoin the 

 ambulacra II and IV, the costal 1 being partly in contact with the interradial 1 h, 

 there being only one advanced plate of 5, and that intervening between the costal 4 

 and the interradial 4 a. The sexual pores of the costals 2 and 3 nearly answer to 

 their respective interradia. The madreporic filter occupies the central space. 



In Pourtalesia ceratopyga, Pl. VII, jig. 51, the water-filter spreads över the greater 

 portion of the system, partly to its outermost margins. The costal 1 is completely 

 united to the rest, but on the left side the costal 4 is wholly separated, by the inter- 

 position of three plates detached from the interradium 5, and both costals adjoin the 

 ambulacra II and IV, while the hind margin of the system is contiguous to the inter- 

 radials 1 b and 4 a. The biviary ambulacra I and V, as in the foregoing species, 

 terminate dorsally far apart from the calyx, and without any trace of radials. 



The calycinal system of Echinocrepis cuneata, Pl. VII, fig. 54, is an irregnlar 

 pentagon. The madreporite spreads nearly över the whole, excepting the costals 1, 3 

 and 4, which are however completely united to the rest, provided Avith sexual pores 

 and not much displaced. The costal 2 is completely invaded by the filter, some of 

 whose pores are seen on its very edge, even in the suture. The radials II, III, IV 

 are absent, but the I and V very distinct, of a fair size, pentagonally lengthened, con- 

 tiguous to each other as in the Ethmophract Spatangi, and to the terminations of the 

 ambulacra I and V. They seem to bear eye-spots. 



Thus in Echinocrepis the calycinal system still presents somewhat of a Spatangoid 

 character, such as this is exhibited by Palaäotropus and Palasostoma, in the dispo- 

 sition of the water-pores and the obliteration of the sutures, while, at the same time, 

 another feature peculiar to the older members of the group '), the contiguity of the 

 ^) Comp. Echinocouus coiiicus, Etudes, Pl. XV, fig. 134. 



