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



ended oxea (PI. XXIII. fig. 1) ; with the large end slightly uneven near the point and 

 tapering rather suddenly ; at the small end tapering very gradually to a very fine point, 

 or irregular ; size very variable, up to about 17 by 0-023 mm. There can be little doubt 

 that these spicules are merely modifications of (1). (3) Much shorter, equal ended, fusiform 

 oxea (PI. XXIII. figs. Ic, Id) ; usually sharply pointed at each end, but with the ends 

 often rather uneven, usually with a rather sharp bend in the centre ; size variable, up to 

 about 0'6 by 0'023 mm. (4) Spicules of a very peculiar form, cladostrongyla (PI. XXIII. 

 figs, le. If) ; each consisting of a slightly crooked shaft of even diameter all along ; ter- 

 minating at one end in an evenly rounded extremity and at the other dividing into a 

 number (usually about three) of very irregular, short branches, like the fangs of a human 

 tooth. Size fairly uniform, up to about 0*52 by 0'0063 mm. These spicules often occur 

 together in bundles, like faggots of wood, sometimes surrounding the larger megasclera ; 

 they also occur fairly abundantly in the dermal membrane, where they are scattered 

 separately. It is well worthy of note that the axial thread itself forks with the forking 

 of the spicule, (b) Microsdera ; of one kind only, viz., trichodragmata (PI. XXIII. 

 fig. Ig), occurring abundantly scattered through the soft parts of the sponge, especially 

 in the dermal membrane, in parts of which they form an almost continuous layer. They 

 have the form of small, oblong bundles, measuring about O'l by 0"01 mm. Though usualty 

 fairly comjsact these bundles seem readily to break up into a multitude of component 

 spicules which are exceedingly fine and hair-like. 



This species is at once distinguished by the presence of the peculiar forked megasclera. 



Locality. — Ofi^ Bahia ; depth, 7 to 20 fathoms. Two good specimens and four 

 fragments. 



Off Bahia ; shallow water. One specimen. 



(?) Ofi" Bahia ; shallow water.' One large specimen and two fragments. The large 

 specimen is composed of two long, straight pieces, which have grown up parallel with 

 one another from a common basal portion, and have fused together for a considerable 

 part of their length. 



Suborder II. CLAVULINA, Vosmaer. 



1885. Olavidma, Vosmaer, Bronn's Klass. u. Ordnung. d. Thieneichs, Porifera, p. 328. 



Sponge t3q3ically corticate. Skeleton usually more or less radiately arranged, with 

 a dermal crust of spicules which may be either of the same form as in the main skeleton 

 or of a special form (spined spirulaj, &c.). Megasclera typically tylostylote. Micro- 

 sdera, when present, belonging almost invariably to the stellate group ; never chelae or 

 sigmata. Spongin usually absent. 



1 According to the inside label ; the outside label had — " Off Bermuda." There can, however, be little doubt that 

 Bahia is the correct locality. 



