418 



COLLECTIONS FROM MELANESIA. 



I append a Table showing the chief variations in the proportions 

 of the spicules : — 



Proportions of Spicules (in millim.). 



In the present collection are some more or less fragmentary- 

 specimens, and two which incrust crabs, all well preserved in spirit; 

 they are either broad, massive, about 25 millim. (1 inch) thick, or in- 

 crusting,! to about 6 millim. thick. The surface is covered with more 

 or less closely-set ridges or monticular elevations, from 1 to 3 millim. 

 high. The colour is pale grey of different shades (a purple colour 

 in one case being apparently derived from a purple sponge which 

 arrived in the same bottle of spirit). The spicules agree closely in 

 form with those of Mediterranean specimens ; and the only notable 

 difference in proportion is that the diameter of the acuate is from 

 2 to ^ less than that of those specimens. The colour is paler than 

 in the Mediterranean forms ; but these exhibit a wider range of 

 variation in this respect than is shown by a comparison of the 

 darkest Australian and palest Mediterranean specimen. Therefore 

 I feel fully justified in uniting the two groups of forms as one 

 species, remarkable for its wide geographical distribution, poly- 

 morphic external habit, and great range of spicular variation. 



Hah. Alert and Thursday Islands, and Prince of Wales Channel, 

 Torres Straits, 3-9 fms. ; Port Darwin, between tide-marks. 



Distribution. Mediterranean (Schmidt); Atlantic (Schmidt); 

 Antigua (Carter); Kurrachee (coll. Brit. Mas.). 



T. increscens, Schmidt, JB. Comm. Unters. deutsch. Meer. ii.-iii 

 p. 115 (off S.W. Norway), differs from these and all described 

 species in having a spinulate head to most of the smooth acuates. 



