REPORT ON THE ECHINOIDEA. 135 



groove is narrow, and the actinostome not very distant from the anterior edge ; the test 

 is comparatively low (PI. XXVIII. fig. 2), with a large number of primary tubercles 

 quite uniformly scattered over it (PL XXVIII. fig. 10), except along the actinal keel 

 where they are somewhat larger (PI. XXVIII. fig. 7). The test is thin but hard and solid, 

 the subanal fasciole is large and broad (PI. XXVIII. figs. 5, 7), and the number of plates 

 comprised in the test is greater than in other species. The spines of this species are 

 proportionally short and stouter than in the other species of the genus. The whole test 

 is moderately covered with small secondary and miliary spines. 



There are four genital openings, three larger than the fourth (the left anterior), which 

 is quite rudimentary; they are situated in the trivium, well separated from the bivium by 

 the lateral ambulacral plates (PI. XXVIII. fig. 12). The anal snout is seen in profile 

 (PL XXVIII. fig. 2.), angular, separated from the test on the abactinal side by a deep, 

 sharp cut. The test seen in profile is quite flattened (PL XXVIII. fig. 2), regularly arch- 

 ing anteriorly, the actinal curve slightly re-entering at the actinostome and convex again 

 towards the anal snout, the abactinal curve very slightly arched towards the posterior 

 extremity, suddenly falling towards the deep notch separating the anal snout from the 

 posterior part of the test. 



The apex and apical system are not coincident, the apex being posterior and the 

 apical system anterior. Immediately adjoining the actinal groove the anterior part of 

 the actinal surface is quite flat (PL XXVIII. figs. 6, 8). Seen from the anal extremity 

 the outline is triangular with rounded angles (PL XXVIII. fig. 4),' with a sUght pos- 

 terior actinal keel (PL XXVIII. fig. 7) to which the anal snout is joined like a button. 

 The outline when seen from the anterior end is also triangular, but with a re-entering 

 angle gradually sloping from the flattened anterior actinal surface to the sunken actinal 

 groove (PL XXVIII. fig. 3). The specimens in alcohol were of a dark claret coloui- at 

 first, but they have gradually faded out to a light violet tint. 



The largest specimen collected measured 98 mm. in length, but fragments of the 

 anterior extremity of the test indicate that this species must attain nearly double that 

 length. 



Both this species and Pourtalesia rosea are characterised by the absence of prominently- 

 marked keels, formed by the concentration of primary tubercles on the abactinal median 

 interambulacral space of the lateral anterior ambulacra and of the posterior abactinal inter- 

 ambulacrum. 



Station 157. March, 3, 1874. Lat. 53° 55' S., long. 108° 35' E. ; 1950 fathoms; 

 diatom ooze. 



Station 298. November 17, 1875. Lat. 34° 7' S., long. 73° 56' W. ; 2225 fathoms ; 

 bottom temperature, 1"3° C. ; grey mud. 



Station 299. December 14, 1875. Lat. 33° 31' S., long. 74°43'W. ; 2160 fathoms; 

 bottom temperature, 1'1° C. ; grey mud. 



