REPORT ON THE ASTEROIDEA. 201 



3. Astropecten polyacanthus, Miiller and Troschel. 



Astropecten polyacanthus, Miiller and Troschel, 1842, System der Asteriden, p. 69. 



Astropecten hystrix, Miiller and Troschel, 1842, System der Asteriden, p. 70. 



Astropecten armatus, Miiller and Troschel, 1842, System der Asteriden, p. 71. 



Astropecten vappa, Miiller and Troschel, 1843, Archiv f. Naturgesch., Jahrg. ix., Bd. i. p. 119. 



Astropecten chinensis, Gruhe, 1865, Jahres-Ber. Schles. Gesellsch. f. vaterl. Cultur, p. 30. 



Astropecten ensifer, Grube, 1865, Jahres-Ber. Schles. Gesellsch. f. vaterl. Cultur, p. 36. 



Localities.— Port Jackson, Australia. Depth 2 to 11 fathoms, 6 to 15 fathoms. 



Admiralty Islands. Depth 16 to 25 fathoms. 



Yokohama, Japan. Depth 5 to 25 fathoms. 



Kobe, Japan. Depth 8 to 50 fathoms. 



Hong Kon?;. Beach. 



Remarks.— The examples from the Admiralty Islands are remarkable for the robust 

 ness and size of the large spines on both the supero-marginal and infero-marginal plates. 

 This is especially conspicuous in one example in which the lateral spines are unusually 

 broad and flattened, the breadth being maintained until near the tip, when it abruptly 

 forms a broad lancet-like point. The same example is also noteworthy from the fact that 

 each supero-marginal plate is armed with a spine ; whereas another dredged at the same 

 time follows the usual rule in this species in having the second, or second and third, supero- 

 marginal plates on each side of the median interradial line unarmed. These points are 

 very interesting, but I scarcely feel justified in giving a name to the variety on the 

 strength of the material at command. This course, however, may perhaps be found desir- 

 able in the future, when more examples from this locality are available for study. 



There is a small Astropecten also from the Admiralty Islands, which, from having 

 been dredged in association with the above-mentioned specimens, might not unreasonably 

 be looked upon as the young phase of this species. I consider, however, that it is distinct, 

 and should be referred to Astropecten velitaris, von Martens. The example in question, 

 which has a major radial measurement of 11 mm., and sixteen supero-marginal plates, 

 has only the two innermost plates in each interbrachial arc armed with spines, no trace of 

 their presence being found on any of the others. This view is strengthened by the fact that 

 in young examples of Astropecten polyacanthus from Port Jackson of even smaller size than 

 this, the supero-marginal plates are characteristically and powerfully armed ; and the char- 

 acters of the paxillse and of the spinulation of the infero-marginal plates are also different. 



The type-specimen of Miiller and Troschel's Astropecten vappa in the Berlin Museum 

 is quite a young form and in bad condition. After the study of the large series of speci- 

 mens from Australia, I have no hesitation whatever in regarding the name as a synonym 

 of the present species, although the type-specimen could independently be scarcely held 

 as available for specific recognition. I have also examined the types of Grube's Astropecten 

 chinensis and Astropecten ensifer in Breslau, and I consider that both of them are with 

 little doubt young stages of Astropecten polyacanthus. 



(zoou CHAT.L. EXI*. — PART LI. — 1888.) 2G 



