418 



COLLECTIONS FROM MELANESIA. 



I append a Tatle showing the chief variations in the proportions 

 of the spicules : — 



Proportions of Spicules (in millim.). 



Mediterranean specimens of I 

 T. dtgitata, nigrescms, am- I 

 Hgiia, muggiana ) 



T. digitata, var., Kurracheel 

 specimen J 



Do., Thursday and Alert Is- 

 lands, Torres Straits, speci 

 mens (2) 



Do., Prince of Wales Channel, ' 

 Torres Straits, specimen ... J 



Do., Port Darwin (Australia) 1 

 specimens (2) J 



Smooth 

 Acuate. 



•29 by 

 ■Oil to -012 



•21 by -007 



•19 by -0063 



•25 by -0063 

 •3 by -0095 



Tibiella (in- 

 cluding heads 

 and their 

 diameter). 



•23 to -25 

 by -0063 



•16 by ^0042 



r about ^228 



L by •ooe 



•22 by -(XMS 



r -2 to -25 by 

 I -006 to •0063 



Fine 

 Acerate. 



■1€ to -2 by 

 ■0016 to •0017 



•14 by ^002 



about 

 ■18 by •0015 



■22 by ^002 



•18 to •ig by 

 •0021 to 0032 



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, 1 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 

 I to I less than that of those specimens. The colour is paler thau 

 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 fuUy 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. 



Di'siribution, Mediterranean {Schmidt) ; Atlantic (Schmidt) ; 

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



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

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

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



