BY E. F. KALLMANN. 283 



centrum, are rarely if ever bifurcate or branched, and their 

 number (actually countable) varies (in the same specimen) from 

 9 to 13. The chiasters (tylasters) form a very thin layer at the 

 surface of the sponge and are scattered through both the cortex 

 and the choanosome - more abundantly, in the former region, 

 especially in the innnediate surrounding of the canals traversing 

 it; they measure from 10 or 1 1 /z up to from 17 to (rarely) over 

 20 fx in diameter, have from 6 to rarely more than 10 moderately 

 stout rays, which are provided with a well-developed terminal 

 knob covered with minute spines, and exhibit a fairly well- 

 marked centrum, the diameter of which may equal or even 

 slightly exceed the length of the rays. The oxyasters are entirely 

 confined to the choanosome, are usually abundant, and vary in 

 maximum diameter in different specimens from about 30 to 

 slightly upwards of 40 ^u; they have from 5 to 9 rays, which are 

 provided over their distal moiety with tubercles, some of which 

 are elongated so that the rays may appear branched. 

 Loc. — Port Jackson. 



Genus Tethyorrhaphis. 



According to their description, the four species, ascribed by 

 Lendenfeld to this genus, are distinguished both by differences 

 in the shape and degree of development of protuberances on the 

 surface, and by a number of points of difference in spiculation. 

 Thus, in the case of 7\ Icevis and 7'. gigantea, the brushes, formed 

 by the skeletal fibres on approaching the surface, are stated to 

 be lacking in the shorter stylote spicules present in the other 

 species; in the same two species and in T. conulosa, asters of two 

 kinds, spherasters and chiasters, are mentioned as occurring, but 

 in T. tuberculata only chiasters; and the peculiar microscleres 

 characteristic of the genus are described as strongylote in T. 

 Iwvis, simply as "diact" in T. tuberculata, and as oxeote in T. 

 gigantea and T. conulosa. I have examined all available ex- 

 amples (some twenty in number) of the genus, including those 

 labelled as the types of the several species; but I have failed to 

 find any differences among them in spiculation, except as regards 

 the size and relative abundance of the several kinds of micro- 



