REPORT ON THE ECHINOIDEA. 145 



*Echinocrepis cuneata (Pis. XXVIL, XXXV. " figs. 8-13 ; PI. XXXIX. figs. 31, 32 ; 

 PI. XLI. figs. 30, 31 ; PL XLIII. fig. 14 ; PL XLV. figs. 44, 45). 



Echinocrepis cuneata, A. Agassiz, 1879, Proc. Am. Acad, vol. xiv. p. 206. 

 Seen from the anterior extremity (PL XXVIL fig. 5) the outline is that of a truncated 

 cone, with rounded corners and a deep re-entering angle formed by the rndth of the 

 actinal groove. Seen from the posterior extremity the broad rounded anal keel project- 

 ing over the anal system (PL XXVIL fig. 4) extends below the general level of the 

 actinal surface, and when seen in profile (PL XXVIL fig. 3 ; PL XXXV.* fig. 11) forms 

 an indistinct hood over the anal system. 



The apical system of this species is compact (PL XXVIL fig. 9), placed in the trivium 

 and separated by the accessory interambulacral plates from the bivium, the genital plates 

 are indistinct, the madreporic body is very prominent ; the interambulacral plates are ren- 

 dered prominent l)y the presence of a single large primary tubercle on each plate replacing 

 the regular uniform granulation of smaller primaries covering the greater pai-t of the rest of 

 the test as in Plate XXVIL fig. 8. The test is covered on the abactinal side with primary 

 tubercles, quite uniformly but irregularly distributed over the plates of the ambulacral 

 and interambulacral systems (PL XXXV.* figs. 9-12). These carry small, slender, fine 

 spines of a moderate length. The space between the primaries is filled with minute secon- 

 dary spines (PL XXVIL fig. 8). Minute triangular pediceUarife are found specially 

 numerous in the depressed median ambulacral spaces. Near the abactinal system a 

 number of larger primary tubercles are placed on the upper plates of the interambulacral 

 areas (PL XXVIL figs. 1, 3, 5, 9 ; PI. XXXV.* figs. 9, 11) ; these carry somewhat larger 

 and longer spines than those on the rest of the test. The actinal side is generally flat 

 with a slight rounded ridge, formed Ijy the actinal keel, extending from the anal system 

 to the actinostome and the indistinct ridges formed in the median line of the anterior 

 interambulacral areas ; there these ridges form lines from which the test slopes to the 

 depressed median lino of the anterior lateral ambulacra. The primary tubercles of the 

 actinal keel are large and closely crowded, extending round the anal extremity (PL 

 XXVIL fig. 10; PL XXXV.* fig. 10). The other primary tubercles of the actinal 

 side are also larger and more distant than on the abactinal side (PL XXVIL fig. 1 ; 

 PL XXXV.* fig. 10); they are again somewhat smaller, and more closely packed on the 

 anterior part of the test towards the ambitus, on the actinal side, and in the anterior in- 

 terambulacral areas. The general ground tint of the test is violet-brown, the spines are 

 brownish-yellow, but when denuded the test is light violet. 



The spines immediately in the actinal groove are longer and larger than any 

 others on the test and slightly club-shaped. The anal system is elliptical, placed on 

 the actinal side of the test on a slightly inclined plane, forming the junction of the 

 actinal and abactinal surfaces at the posterior extremity of the test (PL XXVIL 

 figs. 3, 4, 10; PL XXXV.* figs. 10, 11). The anal pouch is quite flat and 



(ZOOL, CHALL. EXP. PART IX. 1881.) I 19 



