FAUNA OF THE OUTEK WESTERN AREA OF THE CHANNEL. 307 



At Position 58. One specimen ; forming an investing growth on 

 dead Pcden valve, with base strongly hispid, 

 50 X 30 mm. in extent, and with seven large 

 smooth fistular processes 20-22 mm. in height. 

 The differentiation between basal and fistular 

 areas exceptionally well shown. Depth, 49 fath. 



Polymastia agglutinans, Eidley and Dendy. 



Single specimens at Positions 13, 32 or 33 (?), 46, 55, 59. 



Depth, 42-49 fath. 



The form of the specimens is in all cases that of a depressed, more 

 or less regular spheroidal or ovoid mass from 10 to 25 mm. in horizontal 

 measurement, with from one to eight fistular processes of 6 to 12 mm. 

 in height, radiating from different points of the surface, the body of 

 the sponge forming an investing growth cementing together small 

 pebbles and fragments of shell into a compact mass. This peculiar 

 habit is common to all the specimens, and there seems no doubt of 

 their identity with Eidley and Dendy's agglutinans (31), of which the 

 external form and habit is so very similar. Professor Dendy, who 

 kindly examined some slides I sent him and allowed me to see some 

 preparations of his original material, considers that there is no differ- 

 ence of sufficient importance to constitute specific distinction. The main 

 characters of the skeleton are almost identically the same, though in the 

 dimensions of the spicules there is a considerable difference. Eidley 

 and Dendy's measurements for the large tylostyli are 1200 ^ by 15"7 /j. ; 

 for the microsclera, 175 /x by 4 /x. In the specimens here considered 

 the megasclera average from 450 to 500 fx, and sometimes exceed 700 ^, 

 but in no case have I seen one reaching 800 /x. The width of the 

 largest is 14'8 /x. The microsclera average about 140 ^ by 3'7 yu. The 

 difference may be a local one. The megasclera are rather more like 

 those of robusta than those of mammillaris. The microsclera are 

 like those of mammillaris, but with much more pronounced heads. 



The Challenger specimens (two) were taken off the Azores in 

 450 fath. on volcanic mud. 



SUBEEITIDAE. 

 Ficulina ficus (Linnaeus). 



Most of the specimens of this sponge obtained were of the massive 

 carcinoecious form, and generally occupied by a Pagurid, but none 

 were of large size. Occasionally, as where stated in the following par- 

 ticulars, they occurred in the earlier stage of these investments on 

 sliells of molluscs. 



