REPORT ON THE ECHINOIDEA. 139 



species, showing the great elongation of the plates of the test which give it its peculiar 

 appearance. The subanal fasciole is broad, well-marked, and the actinal gi-oove a rather 

 shallow triangularly shaped depression with steep sides (PI. XXII. " fig. 2). In general 

 outline it resembles a very elongated Pourtalesia miranda, and I was at first inclined to 

 regard it as the young of that species. The young specimens of Pourtalesia laguncula 

 collected by the Challenger, seem, however, to leave no doubt regarding the distinct 

 specific characters of this species. Seen endwise, the outline of the test is nearly 

 elliptical (PL XXII. figs. 4, 5) from the two prominent actinal and abactinal keels, 

 which project beyond the general level of these surfaces. Seen from the actinal end 

 (PI. XXII. fig. 4), the actinal gi'oove occupies nearly the whole of the section of the test. 

 As in Pourtalesia laguncula the primary spines are irregularly scattered over the test, 

 and are not specially crowded along the abactinal ridge. The apex of this species is 

 posterior (PI. XXII. fig. 2 ; XXII." fig. 1), and it is remarkable also for its convex 

 actinal surface, so shaped that the greatest convexity is about half-way from the anal 

 snout to the anterior end. Seen from above, the anterior extremity has more the shape 

 of that of such Pourtalesise as Pourtalesia ceratopyga, but is remarkable for the great 

 size of the actinal grove which forms a huge triangular depression (PL XXII.'' fig. 2 ; 

 PL XXII. fig. 1), occupying the whole anterior extremity of the test, on the somewhat 

 flattened actinal surface. The anal snout is also somewhat more flattened than in the 

 other species of Pourtalesiae, more as we find it in Pourtalesia rosea. The outbne of the 

 test, when seen from the actinal side is bottle shaped, with deeply convex sides near the 

 anterior extremity (PL XXII. fig. 1 ; PL XXII.'' fig. 2), widest about half-way between the 

 anterior extremity and the snout, and gradually sloping towards the posterior extremity. 

 The abactinal surface slopes very gradually from the apex towards the anterior extremity, 

 forming a slightly concave line before reaching the anterior edge. It slopes c^uite abruptly 

 towards the level of the anal snout (PL XXII.'' fig. 1). Both the actinal and abactinal 

 keels of this species are quite prominent (PL XXII. figs. 1, 3). The excessive elonga- 

 tion of the odd interambulacral end of the lateral posterior interambulacral and ambu- 

 lacral areas, gives to this species its greatly elongated shape (PL XXI I." figs. 1, 2). 



Pourtalesia phiale seems to be a comparatively small species ; the specimen collected 

 by the Challenger measured 18 mm. The test is extremely thin. In alcohol it is of a 

 light yellowish-pink colour, the spines of a darker tint. 



Station 156. February 26, 1874. Lat. 62° 26' S., long. 95° 44' E. ; 1975 fathoms ; 

 diatom ooze. 



^Pourtalesia rosea (PL XXII.'' figs. 3-6). 



Pourtalesia rosea, A. Agassiz, 1879, Proc. Am. Acad., vol. xiv. p. 206. 

 Fragments of a delicate pinkish Pourtalesia were brought up from Station 272 ; 

 they must have belonged to a large species closely allied to Pourtalesia ceratopyga, and 



