TBTRAXONIDA. 31 



Skeleton typi.alK I'.-imc.l of a network of spiculo-fibre, the primary HUGH of which 



M i upwards :ml outwudi tim :.-. mic r -mtarc . .t" - ular tabM tO ' MfeM 



surfm i>t tin ~|M.ir_'c. where their ends forni the vcrrucae ; the secondary fibre** join 

 the primary at right angles forming rectangular meshes a)>out 1*25 mm. square. The 

 thickness of the primary liltivs is al>out '7 mm., that uf the secondary about *5 mm. 



The ectosomal skeleton consists of fan-like bundles and wisps of spiculcs, isolated 

 en priMTi-iling upwards and spreading out from the terminal main fibres. 



Spicules. Megascleres. Smooth styles, 590 x 25 M, curved, with a mucro at 

 the head cud. 



somal spiculcs, 344 x 12'5 M, sub-amphitylote, fusiform, with a marginal 

 ring of vertical spines at both ends and a terminal central spike at one extremity. 



Microscleres. Palmate anisochelae of two sizes, a large kind 35 ^ long and 107 M 

 broad, with thick shaft; with triangular palmate tooth, 17*5 . long, at the large end, 

 not quite as long nor as broad as the alae ; lower margin of alae convex. Lower 

 central tooth with a curved upper edge produced into a spine. 



A small kind 17 '5 ft long, 6*2 M broad ; upper palmate tooth triangular, rounded 

 above, as broad and as long as the alae ; lower border of alae concave ; lower tooth 

 with simple rounded upper edge. 



Bipocilla varying in length from 5 '5 to 11 M, according to the convexity of the 

 shaft which is usually deeply curved ; lioth ends spathulate, nearly similar, and with 

 crenulate edges, or with 5-7 teeth. 



The tine specimen (No. 184) which constitutes the type of the new species, is 

 24 cm. wide and 25 '6 cm. high. Unfortunately, owing to the very soft nature of the 

 tissues, the sponge has IKJCII broken into many fragments. A short stem expands 

 into a palmate portion, from the edge of which arise several compressed digitate 

 branches, usually with round sphinctrate oscules along one edge ; the oscules lead into 

 a pseudogastral cavity extending nearly to the opposite edge of the branch. The 

 bipocilla of the new species somewhat resemble those of /. sjmtulntus, but the difference 

 in the body form, skeletal arrangement and spimlation arc too many to necessitate 

 detailed enumeration. 



A second specimen (No. 202) has two compressed branches rising from a flattened 

 contracted base, the under surface of which is coated with pebbles. The oscules face 

 each other along the edges of the entering angle. The branches are each about 10 cm. 

 in length, the greatest breadth being 4*5 cm. 



A third specimen (No. 287) of this species, which might, indeed, be regarded as 

 a variety, forms a discoid crust on a small Ophiurid. There are embryos, 340 M in 

 diameter, present, and some, but not all, of these have a plug of peculiar tylote 

 spicules in them, with a ring of anisocheles round the outer end of the bundle. 

 The tylote spicules of the embryo, 161 x 7 '8 M, have a smooth rounded end 

 surrounded by spines, the other end being cylindrical with marginal spines, and a 

 single central spine. 



TOU IT. ml 



