BY E. F. KALLMANN. 517 



processes varying in length from 35 to 70 mm. The specimen is 

 in a much macerated condition, the dermal membrane and most 

 of the superficial fleshy substance having disappeared, leaving 

 exposed the surface of the skeleton. The texture is coarsely 

 tibrous and fairly dense, and the consistency is flexible and 

 moderately tough. The exposed surface, both of the basal plate 

 and of the processes, is irregularly and closely furrowed in the 

 vertical direction. From the surface, at distances of from 1 to 

 2 mm. apart, there project single bristle-like fibres, which are 

 most conspicuous on the processes, where they frequently attain 

 a length of 1-5 to 2 mm.; these fibres no doubt represent the 

 remnants of conuli. 



The skeleton is of the same structure as in J. plicata. In the 

 processes (in which it is but very slightly condensed axially) it 

 consists of numerous more or less longitudinally running, stout, 

 multispicular main fibres, frequently branching and interuniting 

 with one another, and connected by numerous, inter-reticulating, 

 slender transverse fibres. The bristle-like fibres, which project 

 from the surface, arise as branches from longitudinal fibres 

 situated towards the axis, and run surfacewards in a direction 

 obliquely upward and outward; at first they are comparatively 

 slender and paucispicular, but increase in stoutness and become 

 more densely spicular as they proceed, finally attaining a diameter 

 of between 150 and 200//.. Without removal of the sarcode, the 

 pattern of the skeleton is rather difticult to determine owing to 

 very faint outlines of the almost colourless spongin, and to the 

 numerous, mostly longitudinally-directed megascleres lying 

 scattered between the fibres. 



Tylodesma Thiele. 



Dimjnosis. — Axinellida^C?) typically of massive (or rarely in- 

 crusting) habit, the outward form irregular or somewhat com- 

 pressed, occasionally more or less leaf-shaped. Skeleton consist- 

 ing of a more or less irregular network of spicules, or of fibres 

 that are most frequently not very well-marked and reach no great 

 length, or finally, of well-developed spicular fibres. .Spongin 

 present only in i-elatively small amount, or altogether wanting. 



