REPORT ON THE ASTEROIDEA. 3 



In this family will also be included the genera Benthopecten of Verrill, 1 CJieiraster of 

 Studer, 2 and, according to their distinguished author, perhaps also Blakiaster, Perrier, 3 

 and Goniopecten, Perrier. 4 



The diagnosis of Benthopecten is too brief even to indicate with certainty the sub- 

 family to which it belongs. 



CJieiraster probably finds its nearest ally in Pontaster, but is widely separated from 

 that type by the truly remarkable position of the generative organs, which are said to 

 be confined to the outer half of the ray in the form of a pair of long bands — an abnormal 

 structural character, which is certainly not present in Pontaster. The polygonal plates of 

 the paxillse are likewise different. This position of the genitalia is so unusual that I 

 should have been disposed to regard it as an error of observation had it been recorded by 

 a less experienced and careful anatomist than Professor Studer. 



Blakiaster is placed by Perrier in the family Archasteridse, and it is on his authority 

 that I now include it, for unfortunately both the description and the figure convey only a 

 very imperfect idea of the structural and genetic characters of the form. It appears to be 

 remarkably Astropecten-like in many respects, and it might ultimately turn out to belong 

 to the family to which that genus gives the name. In fact I rather suspect that such will 

 be the case, from the presence of the series of small plates intervening between the infero- 

 marginal plates and the adambulacral plates ; and Perrier's remark, " L'anus n'est pas 

 distinct," seems to point in the same direction. 



Goniopecten, as far as I can judge from the characters described — which are chiefly 

 specific rather than generic — will probably be included in the subfamily Plutonasterinse, 

 one of the species approaching in many respects Plutonaster ; but whether all the 

 species can be retained in the one genus is somewhat doubtful. A more exhaustive 

 study of their real structural characters might, however, place the group of species as a 

 distinct subfamily of Archasteridse — to be called the Goniopectininae. 



M. Perrier seems to have had much doubt as to the classificatory position of Gonio- 

 pecten, as in the Liste Methodique (Nouv. Arch., pp. 166-169) that genus is ranked in 

 a distinct family, Goniopectinidse, in the order " Stelleridae valvulatoe" (loc. cit, p. 168) ; 

 whilst in the description of the species on p. 249 the genus Goniopecten is removed to 

 the order " Stelleridse paxillosse," and is there placed in the family Archasteridce. No 

 explanation of this discrepancy is given. With this conflict of opinion on the part of the 

 author, and only an imperfect generic diagnosis as a guide, it is obviously impossible at 



1 Amer. Journ. Sci. and Arts, Sept. 1884, voL xxviii. p. 218. 



2 Sitzungsber. naturforsch. Freunde Berlin, 16. Oct. 1883, p. 130; Anliang z. d. Abhandl. d. I: 

 preuss. Akad. d. Wiss. Berlin, vom Jahre 1884, p. 49, Taf. iv. figs. 8, a, b, c; Taf. v. figs. 9, a, b, c, d, e. 



3 Bull. Mus. Comp. Zobl., 1881, voL ix. p. 28 ; Nouv. Archives Mus. Hid. Nat., 2e Serie, 1884, t. vi. p. 

 265, pi ix. fig. 2. 



* Bull. Mus. Comp. Zobl, 1881, vol ix. p. 24; Nouv. Archives Mus. Hist. Nat., 2e Sene, 1884, t. vi. 

 p. 249, pL iv. figs. 4 and 5 ; pL v. figs. 3 and 4 ; pi. vii. figs. 1 and 2. 



