SPONGITDA. 



599 



deration of the large size of a specimen from Mauritius (probably 

 from deep water) in the National collection : this measures 170 by 

 100 millim. in greatest length and breadth ; the primary fibres 

 project strongly from the paper-like dermis, and the conuli arc 5-10 

 millim. apart ; the fibre shows just the branching arrangement 

 described in 0. collectrix. The species now to bo described agrees 

 remarkably in general characters with the same species, and is also 

 sufficiently large to be called adult. 



14. Oligoceras conulosum. 



Incrusting, strongly flattened from above downwards, forming a 

 leathery crust, but occasionally throwing out flattened, pointed, free 

 lobes from lateral margin ; strongly hirsute above with the very 

 prominent, slender, and pointed conuli, 1-2 millim. high, 2-4 millim. 

 apart at tips : terminated by the single or (more rarely) multiple 

 ends of primary fibres, which stand out about 1 millim. beyond tho 

 dermis. Surface between ends of conuli forming a series of slightly 

 concave spaces (in spirit), smooth, glabrous, of leathery appearance. 

 Colour in spirit dull putty-colour to pale grey ; consistence (when 

 occupied by Spongiophaga) flexible, tough. Main skeleton — pri- 

 mary fibre occasionally branched at apex, about *17 to '27 millim. 

 in diameter; axis composed of closely packed foreign bodies, occupying 

 from -| to T 9 F of the entire diameter : secondary fibres apparently 

 absent. Dermal skeleton composed of irregularly arranged fibres, 

 chiefly straight and parallel to each other, varying in composition 

 from an almost entirely horny to an almost entirely sandy state ; 

 diameter about - 14 to -35 millim., meshes about *35 millim. wide ; a 

 small quantity of free foreign bodies is to be found interspersed in 

 the intervals between the fibres. Tissues between fibres of main 

 skeleton also containing a considerable proportion (about one fourth) 

 of free, small, foreign bodies. Horny matter of fibre normally pale 

 amber-yellow, transparent. Parenchyma very pale brown, trans- 

 parent. 



Hob. Glorioso Islands, 7-10 fms. ; bottom, sand and coral. 



A single specimen in spirit, 60 millim. in extreme diameter at 

 base, 8 millim. in greatest thickness of the same ; the lateral lobe 

 (which seems to have been decumbent) is 30 millim. high, 14 by 4 

 millim. in basal diameter. Tissues infested by a Spongiophaga 

 (Carter) — head oval or subpyriform, long diameter -095 to -013 

 millim., short diameter '006 to -0095 millim. ; filament, diameter 

 •004 to -005 millim. — which has partly destroyed the horny matter 

 of the fibre, and forms sheets in the mesoderm. 



The apparent total absence of secondary fibres is perhaps due to 

 youth or the ravages of the parasite ; the arrangement of the skeleton 

 is that ascribed by F. E. Schulze to Oligoceras collectrix, Schulze, from 



Oligoceras to possess in parts the ordinary reticulate arrangement found in 

 Cacospongia, &c. This observation seriously militates against its generic 

 distinctness. 



