506 " THETIS " SCIENTIFIC RESULTS. 



Megascleres :— (1) Smooth echinating styli, often slightly bent 

 near the base; size 0-25 to 0-4 by 0014 to 0-016 mm. (2) Smooth 

 straight styli of the core ; size 0-45 to 0-5 by 0-008 to 0-012 mm. 



Microscleres : — (1) Sigmata, extremely abundant throngliout 

 the sponge especially in the dermis ; size 0-018 mm. (2) Microxea, 

 scattered or in loose bundles ; size 0-08 to 0-1 by 0-0015 to 0-002 

 mm. (3) Microstrongyla ; these are present in great numbers 

 everywhere ; size 0-01 to 0-02 by 0-006 to 0008 mm. 



The genus is evidently intermediate between Echinoclathria 

 and Ophlitaspongia. 



ECHINOCHALINA, Thiele. 



ECHINOCHALINA RETICULATA, sp. nov. 



(Plate xlv., figs. 25-25a.) 



Stations 48, 53. 



Sponge consisting of a rather loose, irregular, honeycombed 

 network of thin trabeculpe ; the latter are connected — in the 

 dried skeleton — by delicate webs of interlaced fibres which form 

 the walls of the cells. In spii'it examples the gossamer-like 

 partitions are covered with a very thin layer of sarcode ; the 

 epidermal surface exhibits a series of small pores, with here and 

 there a few circular areas covered by a tympanic membrane. 

 There is no trace of oscula, except the pores are to be regarded 

 as such. Texture resilient, and i-ather tough ; colour grey. 



The skeleton consists of a series of horny fibres, which are 

 often trellis-like in arrangement, but near the surface tliey are 

 somewhat plumose ; the primaries measure from 0-1 to 0-2 mm. 

 in diameter, and are densely echinated by smooth, straight, 

 tapering styli, and exhibit a slender coi'e of ill-arranged slender 

 tylostyli and tylota. The secondary fibres are about 0-5 mm. or 

 less in diameter, and internally they either have two or three 

 distinct spicules or are aspiculous. The connecting fibres are 

 very slender and form an intricate network between the primaries 

 and secondaries ; they usually present from three to four echin- 

 ating styli on one side and occasionally one or more slender 

 spicules within. The mesh is generally narrowly oval or oblong 

 and about 0-2 mm. wide. 



Megascleres : — (1) Straight, smooth styli, echinating the fibres j 

 size 0-15 by 0-008 to 0-01 mm. (2) Slender, straight tylostyli, 

 in the fibres ; size 0*22 by 0*004 mm. (3) Straight, slender 

 tylota, with evenly rounded ends; size 0*22 by 0-0045 mm. The 

 latter occur chiefly in the dermal membrane. 



