Catalogue of Non-Calcareous Sponges. 255 



Microsderes. Very beautiful double asters with the abundantly 

 spiny ends separated by a well-developed, smooth, cylindrical 

 shaft. The ends vary from subglobostellate to Latrunculia-\\)s.e, 

 with two whorls of spines, the terminal whorl being smaller, a 

 condition especially distinct in the smaller and slenderer forms. 

 The larger forms measure about O05 mm. in total length, the 

 smooth shaft about one-third of the total length and O0083 

 mm. in diameter, and the heads about 0'029 mm. in transverse 

 diameter including the spines. The smaller forms vary a good 

 deal in their proportions but are relatively slenderer and with 

 longer shafts. The microscleres are abundantly scattered both 

 in the deeper parts of the sponge and in the dermal membrane, 

 but they do not form a continuous dermal crust. 



This very beautiful and well-marked species appears to be 

 most nearly related to Carter's Latrunculia (Spirastrella) corticata, 

 said to come from the Red Sea, both in the arrangement of the 

 skeleton and in the form of the microscleres, but in the latter 

 the megascleres are oxeote. It is at once distinguished from 

 Schmidt's Suberites bistellatus by the absence of distinct heads to 

 the megascleres, and the well-developed, smooth shaft of the 

 microscleres, which form an interesting transition to the unequal- 

 ended discasters of Latrunculia. 



R.N. 319 (18 f.; "orange-yellow"); 475 (x, 20 f.; "heliotrope- 

 purple, fading into a whitish tint below"); 642 (x, 20 f.; " orpi- 

 ment-orange, shading to buff below "); 1171 ; 1179. 



Spirastrella areo/afa, n. sp. 



Sponge sessile, massively lobose, with rounded margin, upon 

 which numerous small vents are scattered. The largest specimen 

 has been dried and now measures about 7^ inches high, 8 inches 

 long, and -14 inches thick ; it thus forms a large mass but it 

 appears to be only half of a divided specimen. Surface in spirit 

 subglabrous but more or less areolated or at least warty. In the 

 dry specimen the areolation is extremely distinct, especially 

 where the cortex is least contracted, the surface being marked 

 out in very distinct polygonal areoke about a quarter of an inch 

 in diameter, separated from one another by tine but sharp raised 

 boundaries, and each area with a slightly roughened raised centre. 

 On the rounded margin of the sponge many of the vents may be 



