TETRAXONIDA. 9 



conglomerations of crystals, 30-45 /x in diameter, are clearly defined owing to their being 

 much more deeply stained than the surrounding tissues. The appearance of capsules 

 in PI. IX. figs. 13, 14, is due to an optical effect. The deep staining and the well- 

 defined spheroidal shape might cause these bodies to be mistaken for organic structures ; 

 they are barely visible when unstained, and it is not easy to separate them from the 

 dehydrated tissues in which they lie, in order to test the action of reagents ; when 

 separated they are found to be soluble in water. 



Localities. The specimens come from six different localities in the neighbour- 

 hood of Winter Quarters, from depths ranging from 10 to 25 fms. Also Kerguelen 

 Island, 25-60 fathoms, ' Voy. Challenger.' 



CiNACHYRA VERTEX. 



(Plate X., figs. 1-14.) 

 1907. Oinachyra vertex Lendenfeld (11a. p. 310). 



Sponge, generally oval, ovoidal, or conical, with long diameter horizontal. Surface 

 with conules, usually oblique and more or less appressed to the surface, arranged in 

 spiral rows, and terminating in tufts of spicules, the conules and tufts wrapping round 

 the body. With well-developed root-tuft. 



Porocalyces, varying greatly in size and appearance, being hemispherical pits with 

 circular orifice, or obliquely directed pockets with slit-like opening ; surface hispidated 

 with trichodal protriaenes. 



With several oscules situated in a more or less circumscribed area on the side 

 opposite the area of greatest development of porocalyces, or at or near the summit of 

 conico-ovate specimens. The oscules were open only in one instance ; they were 

 3*25 X 2 mm. in diameter, with a marginal fringe, and a platform-like spicule below 

 the rim. 



Ectosome, an outer layer of coUenclymse, and an inner of fibrous tissue, with 

 cortical spicules. 



Flagellated chambers eurypylous. 



Spicules. Megascleres. (1) Somal oxeas, 5*5 x • 057 mm., fusiform, tapering 

 gradually to sharp points. 



(2) Choanosomal oxeas 520 x 18 /x, slightly curved. 



(3) Anatriaenes ; cladome, more or less hemispherical, often with apical umbo, cladi 

 at first at right angles, then making a sharp bend ; length 210 /x, thickness at base 70 /x, 

 chorda 300 /x, sagetta 200 fj, : rhabdome 6 ' 5 /x broad at junction with cladome, then 

 narrowing slightly, again thickening slightly, and terminating gradually in a fine 

 sharp point. 



(4) Protriaenes, cladome usually with one long cladus 170 /x twice the length of 

 the other two; rhabdome 7-5 x '019 mm. nearly uniform in thickness in distal 

 half, tapering at proximal end to fine sharp termination. 



2 B 2 



