COLLECTED BY THE SCOTTISH NATIONAL ANTARCTIC EXPEDITION. 449 



Spicules. — (l) Styli. — The shaft is slightly curved, the curve being most marked 

 at a little distance below the head. Length 0"28-0*375 mm. by 0"008-0'01 mm. 

 (2) Tylota. — There is a rather well-marked swelling at each end of the spicule pass- 

 ing evenly into the shaft. The ends are smooth. Length '22-0 '3 mm., with a 

 maximum diameter of 0'005 mm. (3) Onychata. — Scattered or in bundles, in great 

 abundance through the sponge and in the dermal membrane. These spicules are of 

 two kinds : (a) straight, abruptly pointed at one end and tapering to a long point 

 at the other ; spined ; length 0'125— 0'15 mm. by 0"0025 mm. ; (b) rather longer, 

 more slender and more finely spined than (a), often slightly curved ; one end abruptly 

 pointed, the other tapering to a long and very fine point ; at a short distance, 

 usually '02-0 "03 mm., below the blunt end there is a rounded swelling ; length 

 of the spicule 0"15-0'175 mm. by about O'OOl mm. 



The spicules, both megascleres and microscleres, vary but little in size in a single 

 specimen, or from one specimen to another. 



The megascleres are very similar in shape to those of Tedania suctoria Schmidt. 

 They are below the average size as stated by Lundbeck (13) for that species, though 

 their measurements are about the same as the lowest measurements for the species 

 given by the same author. The two species differ in external appearance, as 

 Tedania scotise does not possess papillse, and in the size and shape of 

 the microscleres. 



Onychata with a similar rounded swelling have been noted in three species, 

 namely, in Tedania pectinicola Thiele (19), T. charcoti Topsent (23), and T. murdochi 

 Topsent (25). In addition to other differences in spiculation, all these species possess 

 tornota as dermal spicules and cannot be confused with the new species. 



The term onychata, recently suggested by Professor Topsent (25) for the 

 characteristic microscleres of the genus Tedania, is here adopted in preference to 

 the older term, rhaphides, usually applied to them. 



Sub-family mycalin^:. 

 Mycale simonis (Eidley and Dendy). 



Station 483. Entrance to Saldanha Bay, 25 fathoms. 21st May 1904. 



The collection contains one complete specimen and two or three fragments of 

 this species, all growing at the base of hydroid colonies, and partly encrusting 

 their stems. 



The complete specimen is a small, oval, cushion-like mass about 25 mm. in its 

 greater diameter. In spirit it is pale grey in colour, with an even, but minutely 

 hispid surface. 



The Scotia specimens agree exactly with the type (15) in the arrangement of the 

 skeleton and in the shape of the spicules. There are a few slight differences in the 

 measurements of the latter. The subtylostyli are 0'3-0*425 mm. by O^OI-O'OIS mm. 



