FAUNA OF THE OUTER WESTERN AREA OF THE CHANNEL. 309 



acter that is definitely shown in the longitudinal and the transverse 

 sections, but in all other respects it conforms so closely with the 

 descriptions of dongata that I can only regard it as the same species, 

 and conclude that the point referred to has been overlooked. 



The specimen forms a slightly bent column of 60 mm. in height, 

 widening gradually in diameter from 5 mm. at base to 8 mm. near the 

 middle, beyond which it is sub-cylindrical, with the apex rounded. 

 The colour in spirit is pale yellowish white. There are numerous 

 small oscula scattered at irregular intervals over a great part of the 

 surface, without any particular reference to the apex. The specimen 

 was broken from its attachment, but two small rootlets are preserved 

 in connection with a rounded base. The texture is very tough and 

 compact. 



The skeleton consists of a very compact central axial core of stylote 

 spicules with a quantity of spongin, surrounded by a clear area, beyond 

 which is a ring of spicular belts running parallel to the axial 

 core, the component belts following a spiral course. In the trans- 

 verse section these belts are marked off from one another by 

 slender strands of few spicules that radiate sub-spirally outwards and 

 upwards from the axial core, across the clear area, and through the 

 belts to the surface. Similarly, spicular strands separate off indepen- 

 dently from the outer side of the belts themselves and branch in a 

 spreading fashion on their way to the surface, beyond which many of 

 the spicules extend. At the surface they combine with innumerable 

 radiating fasciculi of smaller and shorter styli, to form the dermal his- 

 pidation, which has the form of a closely approximating series of 

 defensive brushes. 



The spicules of the longitudinal belts and their branches, and those 

 of the axial core, are slender styli, often slightly curved, with simple 

 rounded base, sometimes faintly tylote, and with sharp tapering points. 

 They range from 900 to 1600 yu (averaging 1300 /x) in length, and 

 from 7 to 11 yu (averaging 9 /a) in width. The spicules of the dermal 

 fasciculi, which are also present in small numbers, scattered between 

 the longitudinal belts and the surface, are styli of 200 to 440 jj. 

 (averaging 280 n) in length, and 2 to 6"5 /x (averaging 4-5 fx) in width. 

 Many of them are simple, but a large number — perhaps the majority — 

 are strongly tylote, and usually with a second ring-like expansion beyond 

 the basal one, as in the spicules, e.g., of Suheritcs carnosus. The bases of 

 these dermal tylostyli are extremely like those of the latter species, 

 and in the vertical view of the outer surface there is a striking simil- 

 arity between the two sponges. 



The noteworthy points of difference from Eidley and Dendy's original 



