COLLECTED BY THE SCOTTISH NATIONAL ANTARCTIC EXPEDITION. 437 



Length 1-1 '5 mm. by 0*027-0*03 mm. (2) Tylostyli of the main mass of the 

 cortex. — These have typically a well-marked, usually trilobed head, but sometimes 

 the head is less well developed, so that the spicules become subtylostyli or even 

 styli. The shaft is slightly curved and strongly fusiform. The length is 

 0*45-0*6 mm., with a maximum thickness of 0*027 mm. (3) Small subtylostyli of 

 the dermal brushes and of the bundles scattered through the choanosome. — These 

 have a slightly fusiform and slightly curved shaft. Their length is 0*14-0*24 mm. 

 by 0*005 mm. 



Polymastia littoralis resembles Polymastia corticata Eidley and Dendy (15) in 

 having a thick, dense cortex, but otherwise the species differ. The arrangement of 

 the cortical skeleton (except in the papillae) is somewhat similar, but the choanosomal 

 skeleton is different, strong well-defined fibres being absent from P. corticata. The 

 spicules differ also in shape and measurements. P. corticata is, moreover, a deep-sea 

 species, having been taken at various depths up to 1200 fathoms. 



In Polymastia meandria Wilson (28), on the other hand, the spicules, though 

 differing in details of measurements, are very similar in shape to those of Polymastia 

 littoralis, but the structure of the cortex is different both in the papillae and in the 

 main body of the sponge, nor is the cortex in P. meandria nearly as thick as that 

 of the new species. 



Polymastia was for long considered a typical deep-sea genus, and the Scotia 

 specimen is therefore interesting in having been taken between tide-marks. Only 

 two or three other species of Polymastia have been so obtained. Even the widely 

 spread Polymastia mammillaris has never been recorded between tide-marks, except 

 on a few occasions for the coast of Ireland. 



Family Chondrosiid/E. 

 Chondrosia reniformis Nardo. 



Station 24. Porto Grande, St Vincent, Cape Verde Islands, shore, N.E. 1st 

 December 1902. One specimen. 



Only one specimen was obtained. It is more or less pear-shaped, but rather 

 flattened. It is 39 mm. in length. 



The colour in spirit is pale greyish yellow, tinged with brown on the upper 

 parts of the sponge. 



The species has apparently a wide geographical range. It has been recorded 

 from the Mediterranean and Cattegat ; the Gulf of Aden and off Ceylon ; off Amboina, 

 Christmas Island, Galapagos Islands, and off the coasts of Australia. 



Chondrosia plebeja Schmidt. 



Station 499. St James's Bay, St Helena, 15° .57' S., 5° 40' W., 30 fathoms. 

 2nd June 1904. 



