238 THE VOYAGE OF H.M.S. CHALLENGER. 



Latrunculia bocagei, Ridley and Dendy (PI. XLIV. fig. 1 ; PL XLV. figs. 8, 8'^'). 



1886. Latrunculia Bocagei, Ridley and Dendy, Ann. and Mag. Nat. Hist, ser. 5, vol. xviii. 



p. 492. 



Sponge (PI. XLIV. fig. 1) massive, sessile; the two specimens in the collection are 

 both subglobular and have been attached to foreign oljjects Ijy constricted bases. The 

 strongly convex upper surface' is covered with very numerous papillifomi processes ; a 

 few of these, at the top of the sponge, are rather larger than the rest, in form conical, 

 and each with a small oscular opening at the apex. The remainder are cylindrical rather 

 than conical in form, narrow, somewhat elongated and abruptly truncated at the top, 

 where no distinct opening can be seen ; evidently they are raised pore-areas as in 

 Latrunculia apicalis. There is a distinct, thick, leathery cortex, easily separable from 

 the underlying tissues. The larger of the two specimens measures about 38 mm. in 

 diameter. Colour in spirit very pale yellow. One specimen, which was found in the 

 same bottle with the dark- coloured specimen of Latrunculia apicalis, is, like it, of a dark 

 chocolate colour throughout ; but since the other specimen, which was in another bottle, 

 is of a very pale yellow colour, we must attribute the brown coloration of the former 

 specimen to the action of some staining substance dissolved in the spirit and probal)l}' 

 derived from some other sponge. Texture of the cortex tough and leathery, of the inner 

 parts fairly compact, but rather soft and spongy. Surface fairly smooth between the 

 numerous processes, but rather harsh to the touch and wrinkled in places, especially 

 around the oscula. Oscula distributed singly on the tops of conical eminences. Pores 

 (doubtless arranged as in Latrunculia ajncalis, though this has not been absolutely 

 proved). 



Skeleton. — Arranged as usual in the genus, with an external layer of the discasters, 

 and an internal, confused mass of smooth styli, with ill developed fibres, making up the 

 main skeleton. In both specimens of this species, however, the layer of " chess-man " 

 spicules is backed up by a thick cortical layer of densely interlacing stylote spicules, as 

 in the Kerguelcn specimen of Latmnculia apicalis, and not by a mere film of interlacing 

 spicules as in Latrunculia hrevis. 



Spicules. — (a) Megasclera; smooth, slightly crooked, more or less hastately pointed 

 styli (PI. XLV. fig. 8), measuring about 0*6 by 0-018 mm. (6) Microsclera; discastra, 

 differing somewhat inform from those of any other known species ; each spicule (PI. XLV. 

 fig. 8a) has a slightly expanded base armed with two whorls of spines, then comes the 

 smooth, stout shaft bearing three distinct, subequal whorls, well separated from one 

 another, and ending in a crown-like tuft of spines which follows close upon the last whorl. 

 Each of the three disc-like whorls is deeply notched along the rim, but the notches are 

 not equal all the way round. Length of the spicule about 0'07 mm., diameter of whorls 

 about 0'03 mm. 



