SPONGES. 199 



about 0m'(9 millitn. by 0*025 millim. ; sizes indiscriminately mixed in the body of the 

 sponge, partially sorted out as described above in the digitiform processes, measuring 

 in the surface brushes usually only about - 377 millim. by 0"0082 millim. 



This variety differs from the typical form of the species in the absence of the special 

 dermal skeleton of slender oxea placed tangentiallv. 



R.N. -29a (Stat. XLIIL, off Kaltura, 22 fathoms). 



Collocalypta, n. gen. 



Axinellidaj consisting of a basal crust, from which isolated digitiform processes spring 

 vertically upwards. With a thick, collenchymatous ectosome which, in the 

 digitiform processes, is penetrated by wide longitudinal canals communicating 

 with the exterior by groups of small canals ending in dermal pores. Skeleton 

 consisting in the basal portion of erect plumose columns of megascleres ; in the 

 digitiform processes of an axial core of spicular fibre from which loose bands of 

 spicvdes radiate outwards between the longitudinal canals to surface conuli. 

 Spicules more or less cemented together by spongin. Without microscleres. 



This remarkable genus bears a very striking superficial resemblance to Ciocalypta, 

 from which, however, it differs widely in the presence of the thick, collenchymatous 

 ectosome and the typically axinellid (plumose) character of the main skeleton, as well 

 as in the total absence of dermal skeleton (compare, however, Ciocahjpta tyleri, var. 

 aberrant), and the presence of abundant spongin cement. 



Collocalypta digitata, n. sp. Plate VII., fig. 6 ; Plate XIIL, figs. 1, 2. 



Sponge (Plate VII., fig. 6) consisting of a flat, wide-spreading, encrusting base, 

 about 8 millims. thick, from which arise erect digitiform processes widely separated 

 from one another by irregular intervals. These processes vary much in size, the 

 largest in my possession is about 53 millims. high by 8 millims. in diameter in the 

 middle. They usually taper to a sharp apex and are, as a rule at any rate, 

 unbranched. The surface of the basal crust, between the processes, is smooth or 

 nearly so, but it may be slightly hispid, and it is covered by a good deal of foreign 

 matter in places. The digitiform processes have a distinctly conulose and, at the 

 same time, longitudinally corrugated surface. They bear no visible vents, but 

 numerous minute pores (now all closed). The colour of the sponge (in spirit) is pale 

 grey ; the consistence tough and fleshy. 



The skeleton in the basal crust consists of stout, erect, plumose columns of spicular 

 fibre, closely crowded together. The spicules are arranged in the typical axinellid 

 manner, with their outer ends projecting obliquely upwards and outwards, while their 

 inner portions are cemented together by a considerable amount of spongin. Each 

 column is continued through the ectosome as a loose tuft of more slender and longer 

 spicules than those which compose its deeper portion, and the apices of these spicules 

 commonly project beyond the surface. There is no dermal skeleton. In the digitiform 



