DENDY— REPORT ON THE HEXACTINELLID SPONGES (TRIAXONIDA) 217 



Euplectella aspergillum. The latter species, however, has only two tentacles to each 

 hydranth, while our form certainly seems to have at least three in some cases. Moreover 

 the tentacles in Schulze's species are much longer than in ours, assuming both to be 

 retracted to approximately the same extent. Schulze also speaks of a delicate, annulated 

 perisarc tube in his species. 



It seems probable therefore that the commensal hydroid of Heterorete belongs to a 

 distinct species from that of Euplectella and, provisionally at any rate, it may be named 

 Amphibrachium infestans. 



Register No. and Locality, cxv., Salomon, 3.7.1905, 0. 120 — 150 fathoms. 



Genus Saeostegia Topsent [1904]. 



The sponge forms a coral-like colony of stony hardness, the more or less cylindrical, 

 tubular or solid branches ramifying chiefly in one plane and sometimes anastomosing. 

 The rather close dictyonal framework of the skeleton is made up of stout trabeculse. The 

 separate spicules consist of (l) dermal and gastral hexacts, in which one ray is fi-equently 

 more or less completely reduced, (2) spinose hexacts, which tend to become incorporated 

 with the dictyonal framework, (3) dermal sarulse, (4) uncinates, (5) oxyhexasters, 

 (6) discohexasters. 



This well-characterised genus was founded by Topsent in 1904 for a remarkable 

 sponge obtained by the " Princess Alice " and the " Talisman " in deep water off the Cape 

 Yerde Islands, and named Sarostegia oculata. 



In the same year Schulze [1904] proposed the genus Ramella for fragments of 

 a similar sponge collected by the "Valdivia" expedition near the Cape Verde Islands 

 and Sumatra respectively. There can be little doubt that the specimen from the Cape 

 Verde Islands at least is both generically and specifically identical with Topsent's. 



Curiously enough, in the same year again, H. V. Wilson [1904, p. 84] proposed 

 a genus, Sclerothamnopsis, for some fragments collected by the "Albatross" expedition 

 in the Eastern Pacific, which may very well be generically identical with Topsent's and 

 Schulze's specimens. In neither of these two latter cases, however, was the material 

 sufficiently well preserved to afford the basis of a satisfactory generic diagnosis. In 

 .the "Valdivia" material the only separate spicules found were the uncinates. In the 

 " Albatross " fragments the following are described, although in the generic diagnosis it 

 is stated that the free spicules are not known with certainty : — 



(1) Spinose hexacts (similar spicules occur in the " Sealark " material). 



(2) Slender, smooth oxydiacts, always broken (probably broken uncinates, which, 

 in the " Sealark " material, may have the spines very feebly developed, so that they 

 resemble smooth oxydiacts). 



(3) Oxyhexasters (similar spicules occur in the " Sealark " material). 



(4) Pinnules of peculiar form, with the distal ray enormously swollen and beset with 

 very short spines. Wilson remarks that these pinnules are very few in number but so 

 peculiar that it seems likely that they belong to the sponge. On the other hand, in the 



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