274 
THE VOYAGE OF H.M.S. CHALLENGEE. 
The specimen on which the species is founded is in the British Museum collection. It 
much resembles in general appearance the specimen figured by Schmidt/ and, as already 
suggested, it is possible that Schmidt’s sponge is identical with Placospongia intermedia. 
Incertse sedis. 
Antares,^ n. gen. 
Sterrastrosa in which the megascleres are oxeas and tylotes, the microsclere a disci- 
form sterraster. 
Antares euastrum (0. Schmidt). 
StelletUnopsis euastrum, O. Schmidt, Spong. Meerb. v. Mexico, p. 76, 1880. 
Sponge. — “ A fragment of a white branch 20 mm. long, of the thickness of a quill.” 
Spicules. — I. Megascleres. 1. Oxea, fusiform. 2. Tylote. 
II. Microscleres. 3. Sterraster, disciform. Other asters absent. 
Habitat. — Grenada, West Indies; depth, 170 fathoms. 
Remarks. — As I have not seen this sponge I can only give Schmidt’s description ; 
imperfect as this is, it is sufficient, if correct, to show that the sponge is not a Stel- 
lettinopsis. Since the sterraster is disciform, and the cortex does not appear to be sub- 
divided into plates, it is probably more nearly related to Erylus than to Placospongia ; 
further it is possible that trisenes and asters are present, but that Schmidt overlooked 
them, and in this case its alliance with Erylus would be very close. In any case the 
association of a tylote with a sterraster seems to involve the creation of a new genus. 
Suborder III. MICEOSCLEEOPHOEA. 
Choristida in which megascleres are absent ; the characteristic microscleres are either 
tetractinose asters, candelabra, or minute triaenes. 
Family III. Thrombida:. 
Microsclerosa with trichotriaenes, and sometimes a peculiar form of amphiaster. The 
cctosome is thin and not sharply defined from the choanosome. The mesoderm is a 
dense collenchyma, containing numerous large granular cells in addition to collencytes. 
The canal system is diplodal. 
* PI. vi. fig. 15, Spong. Atlant. Gebiet., Placospongia melobesioides, 0. Schmidt. 
' Antares, the name of a star. 
