HOLOPNEUSTES. 333 



real description. This is justified because it is clear thac Agassiz intended, when 

 he suggested the name in 1841, that Holopneustes should be the name of these 

 Echini with highly specialized ambulacra; this is unmistakable from his ac- 

 companying remarks. It is not reasonable that his intent should be nullified 

 by a mistake in identifying one of Leske's inadequately described, and poorly 

 figured species, especially when that mistake was rectified at the first opportunity. 



The simple method suggested by Mortensen (1904, Dan. Exp. Siam: Ech., 

 p. 102) for distinguishing Holopneustes from Amblypneastes by means of the 

 arrangement of the ambulacral tubercles, works very well and is a great con- 

 venience in distinguishing specimens of the two genera, when confused in the 

 same lot, as they commonly are ! 



Three species of Holopneustes have usually been recognized but Mortensen 

 has suggested that inflatus and purpurascens may be identical, and this is the case, 

 as the material now at hand shows that the characters, supposed to be specific, 

 are not constant. Mortensen (1904, Dan. Exp. Siam: Ech.) writes both inflatus 

 and purpurascens with Liitken as the authority, and states that the types are 

 in Copenhagen. While it is true that the names were suggested by Liitken, they 

 were published by A. Agassiz and so far as we know were not even used by Liitken 

 in print. It is hard to see therefore why they should be credited to Liitken. 

 Dr. Mortensen is however consistent in this, for he quotes several of Agassiz 

 and Desor's species, as from Valenciennes, although they were simply manuscript 

 names of the latter, on museum labels. As for the location of the types, it is a 

 question which cannot be settled, for Mr. Agassiz never definitely designated 

 type-specimens. But there are specimens in the M. C. Z. collection, on which 

 the descriptions and figures published were based, and these, by some at least, 

 would be considered the type-specimens. In uniting the two species, the name 

 inflatus is retained because it has "page-precedence" in publication, because it 

 is shorter, and because purpurascens is often inappropriate. 



More than half the specimens of Holopneustes at hand seem to be neither 

 porosissi7nus nor inflatus, and a third species, pycnotytus is therefore described. 

 The three species are all from southeastern Australia and Tasmania and are not 

 even reported from elsewhere. 



They may be distinguished as follows : — 



Interambulacral plates fairly numerous (22-25 in specimens 22 mm. h. d., about 46 

 in specimens, 48 mm. h. d.), their tubercles small; areoUv of primaries only 

 occupying about half height of plate, and forming a well-spaced vertical series 

 on each side of interambulacrum. 



