BY E. F. KALLMANN. 403 



between the genera Mycale and Hamacantha. After the most 

 thorough search, however, I have failed to find any such spicules, 

 and am confident, therefore, in the assertion that those observed by 

 Lendenfeld must have been of foreigni origin. In support of this 

 also is the fact of the very close correspondence in spiculation 

 between M. ridleyi and certain other species of Mycale, which we 

 well know to be without diancistra. 



Both specimens are dry, and bear every appearance of having 

 underg-one complete maceration; here and there only, they show 

 the faintest traces of what was probably a continuous and well- 

 defined dermal membrane. The specimens were in this same con- 

 dition, no doubt, when Lendenfeld described them — as may be 

 judged from the figure he has given of the type-specimen. Accord- 

 ingly, in relying upon that figure and the following description of 

 external features of the species as aids to its identification, one 

 must allow for the possibility that the therein indicated trabecular 

 structure of the sponge may be wholly internal, and, in the un- 

 damaged specimen, concealed from view by the dermal membrane. 



Description. — The sponge, which is probably semi-encrusting or 

 submassive at the outset of its growth, grows up into one or several, 

 usually branching, stout stems, which may attain a height of 500 

 mm. These stems (and their branches) are made up of anastomos- 

 ing trabeculae. The latter are roughly circular in cross-section, and 

 measure from 3 mm. to (rarely) 7 mm. in diameter; their surface 

 (in the absence of dermal membrane) i^ highly rugose. In the 

 more central portion of the stems, especially in the older parts of 

 the sponge, the trabeculae become more or less fused together, thus 

 to a great extent losing their individual outline, and tending in 

 some measure to give rise to a solid axis; the (simple or branched) 

 superficial trabeculae, for the most part, project separately out- 

 wards, in an obliquely upward direction. The characteristic 

 appearance of the sponge is well portrayed in the figure which 

 Lendenfeld has given of the type-specimen. This, which is much 

 less stoutly proportioned than the second specimen, measures 380 

 mm. in height, and has attached to it, near the top, three large 

 bivalve shells, over the surface of which it has formed a thin crust. 



