Catalogue of Non-Calcarco7is Sponges. 21 



Microsderes^ small triclentate isochelfe, with fairly stout strongly 

 curved shaft and small but distinct triangular flukes. Length of 

 the whole about 0-016 mm. These spicules are thickly scattered 

 through the soft tissues. 



This very interesting species is evidently closely related to the 

 succeeding (Z>. carnosd). 



R.N. 1163 (x). 



Desmacidon carnosa, Carter, sp. 



Fibiilia carnosa, Carter, A.M.N.H., January, 1886, p. 51. 



This species closely resembles the preceding ( D. intermedia)., 

 with its characteristic branched external form and strong 

 spicular fibre composed of densely packed oxea, breaking up at 

 the surface into a densely radiate dermal skeleton. The micros- 

 cleres, however, are only minute C -shaped sigmata. 



I have no doubt, from comparison with D. intermedia., that this 

 is a Desmacido7i with i-educed or imperfectly developed chelfe. 

 Even the sigmata appear sometimes to be absent (e.g. R.N. 354). 



R.N. 354 (19 f ; "bright orange-scarlet"); 402 (x, 19 f ; "dull 

 red"); 725 (s. 5; "orange-red"): 726 (s. 5; "orange-scarlet"); 

 852 (s. 9). 



B.M. d. 112 ('' Fibulia carnosa'' ; Reg. 86-12-15-372). 



Desmacidon (1) arenifibrosa, n. sp. 



Erect, short-stalked, palmo-digitate, very irregular ; branches 

 short, blunt, compressed or subcylindrical. Surface subglabrous, 

 very minutely reticulate ; in parts with much projecting fibre, 

 in parts minutely conulose. Vents small, scattered. Com- 

 pressible, resilient, tough. Greyish-yellow in spirit. 



Skeleton. The main skeleton is a very definite and fairly 

 uniformly distributed but not very regular reticulation of 

 stoutish pale coloured horny fibre, almost filled throughout with 

 sand and broken spicules. The primary fibres, radiating to the 

 surface, are about 0-1 mm. thick and the connecting fibres are 

 rather slenderer. The meshes of the network ai'e wide but 

 extremely variable. There is a very well-developed, close-meshed 

 dermal reticulation, composed of sand and broken spicules and 

 with small rounded meshes. 



