_. • ECHINOIDEA. II. 



94 



specimen really came from that locality. Further, since the tyj^e specimen of Wyv. Thomson was 

 taken at St 45 (38° 34' N. 72° 10' W. 1240 fathoms)', and only two specimens are mentioned in the 

 « Challenger -Report, one of which (St. 191) is no true A. rustrata. it seems not hazardous to suggest 

 that «Bay of Biscay and Coast of Portugal:; was wrongly named among the localities of A. rostrata. 

 Both the localities named in the « Challenger »-Report, p. 194, are thus wrong; on p. 220 the locality 

 Davis Strait is rightly named. 



A few remarks must be made on the pacific species, Acropsis fulva (A. Ag.) The structure of 

 the test has been very elaborately worked out by Professor Agassiz (Pan. Deep-Sea Ecli. p. 194— 97, 

 PI. 61, 62), and the spines and pedicellarise have been described and figured by de Meijere (v.Siboga>- 

 Ech. p. 195. Taf. XXIII. Fig. 481 — 87). Having examined some specimens from < Albatross- St. 3361 and 

 3399 in the U. S. National Museum I am able to give a little additional information. In the shape 

 of the tridentate pedicellarise I do not find any distinct difference from ^i. rostrata; I have seen none 

 with meshwork in the blade. The rostrate pedicellarite (only one specimen foinid) differ distinctly from 

 those of ^i. rostrata (PL XV. Fig. 34); the blade is shorter and broader than in that species and some- 

 what serrate at the lower end. — In the elongate specimen from the .Challenger^ St. 191 I find the 

 tridentate pedicellaria; somewhat different (PI. XV. Figs. 6, 12, 27). In the larger ones the edges in 

 the lower part of the blade are very irregular, somewhat thickened or thorny, and there may be a 

 rather well developed meshwork. The smaller ones have upon the whole shorter and broader 

 valves than is the case in ^{.Julva and rostrata, and there is often some meshwork developed already 

 (PI. XV. Fig. 27, com]), with Fig. 29). These small differences, in addition to those pointed out by Pro- 

 fessor Agassiz (Pan. Deep-Sea Ech. p. 194), may perhaps tend to show that this specimen from the 

 Arafnra Sea represents a third species, different from A. Jiilva, though certainh- nearer related tt) that 

 species than to A. rostrata. rnfortunateh' the figures of pedicellari;c given by Dr. de Meijere are so 

 little detailed that it cannot with any certaint\' be concluded from them whether his specimens agree 

 in regard to the pedicellarise with ^J. fnlva or witli the vCliallenger^-specimen from the Arafnra Sea- 

 This question about a third species of ^Icropsis must be left undecided for the present; but the main 

 thing here was to show that the elongated form from the Arafnra Sea is not ^i. rostrata. and this, I 

 think, has been put beyond doubt. 



Also on Acestc bcllidifcra a few remarks must be made here. (1 ha\e examined a specimen 

 from the Challenger St. 8 in the British Museum, and another from the .Mbatross JSt. 2117, which 

 Professor Ralhljun most liberally lent me for examination). First as regards the name - /rt'.vA', though 

 apparently so original, it is perhaps a little doubtful if it can be maintained, tlie name Acrsta having 

 been used alread\- in 1855 by Adams for a bi\alve mollusc {Lima cxcavata). .Still the ending of these 

 two names is really different .so that 1 do not think it necessary to alter the name Acestc. (It might, 

 otherwise, easily be done .sufficiently e.g. by adding only an s , so that the name would be easily 

 recognizable). — Regarding the structure of the test I have nothing to add to the careful analysis 

 given thereof by Loven; especially the apical system is .seen by Lo v en's Figure (Pourtalesia. PI. XX. 

 237) to differ considerably from what is seen in the Mg. 7. PI. XXXIII. a. of the Challenger Report. 



The pedicellaria; have partly been figured by Professor Agassiz, but not all sufficiently de- 



' 'The Atlantic 1. p. 3S1. 



