DENDY—NON -CALCAREOUS SPONGES 117 



26. Thrinacophora cervicornis Ridley and Dendy. 



Thrinacofhora cervicornis Ridley and Dendy [1887]. 

 Thrinacophora cervicornis Hentschel [1912]. 



This species is represented in the collection by two small specimens. The 

 branching, so far as the specimens . show, is dichotomous and in one plane, the 

 branches being very short and bluntly rounded off. Surface sparsely hispid owing 

 to the long, slender styli, which project for nearly two millimetres, with shorter 

 projecting styh between. The two specimens are very similar to one another in 

 appearance and closely resemble the young antlers of a stag " in velvet." Total 

 height of each about 20 mm. ; diameter of main stem and branches about 3-5 mm., 

 but variable. Colour in spirit light brown. 



There is a very stout skeletal axis composed of a dense reticulation of stout 

 and rather short oxea. This is surrounded by a comparatively thin layer of soft 

 tissue in which loose bundles of very long styli run lengthwise. Similar styU, 

 with their bases implanted in the central axis, extend through the outer layer and 

 for a long distance beyond the surface. These are arranged singly and each is 

 surrounded, where it leaves the surface, by a radiate tuft of comparatively short 

 and very slender styli. There is no conspicuous spongin in any part of the 

 skeleton (in balsam preparations). 



Spicules. 1. Oxea of the central axis; rather short, stout, distinctly 

 but not very strongly curved or angulated in the middle, usually fairly 

 gradually and sharply pointed at each end. Size fairly uniform, about 0-26 by 

 0-013 mm. 



2. Large styH, running lengthwise in the outer part of the sponge and also 

 projecting more or less at right angles from the surface. These spicules are stoutest 

 at the base and from there taper very gradually to very fine points. They 

 measure about 2-24 mm. in length by 0-02 mm. in thickness at the base. They 

 are shghtly curved. 



3. Small styli of the radiate surface-tufts ; very slender and finely pointed ; 

 measuring about 0-55 by 0-0043 mm. 



4. Trichodragmata ; occurring in immense numbers in the outer part of the 

 sponge ; each bundle rather long and narrow, measuring about 0-1 by 0-0082 mm., 

 often curved, easily separating out into trichites. 



In spite of some slight apparent differences in spicular proportions, especially 

 as regards the smaller size of the large styh, I think that there can be no reason- 

 able doubt that we have here two small and probably young examples of the 

 Challenger species described by Mr. Ridley and myself under the name Thrina- 

 cophora cervicornis. 



In the Challenger Report the length of the trichodragmata is given as 0-0126 

 mm. It should be 0-1 mm., as determined by re-measurements of the type. 



