602 COLLECTIONS FROM THE WESTERN INDIAN OCEAN. 



GUMMINIDiE. 



Gurnminese, Schmidt, Spang. Exist. Alg. p. 1. 



Gummiuida, Carter, Ann. fy Mag. N. H. 1881, viii. p. 248. 



I retain this group provisionally at the commencement of the 

 Silicea, but believe it will ultimately have to be placed near the 

 Tetractinellida. 



18. Chondrilla mixta. 

 PChondrilla mixta, Schulze, Zeitsch. wiss. Zool. xxix. p. 116. 



Prof. Schulze's description of his species is scarcely sufficient for 

 me to determine its relations to the present specimen, as he does 

 not mention the size and exact form of the spicules. It agrees 

 with the present form in having two kinds of spicules, stellates and 

 globostellates, in having a fibrous outer layer about 1 millim. thick, 

 and in the distribution of the spicules in the substance. On the 

 other hand the sections of this (very young) specimen exhibit but 

 scanty traces of the system of subcortical canals which appears to 

 be so well developed in the Red-Soa species, and the colour (in 

 spirit) is pale brown or buff rather than " pale grey, speckled with 

 brown." The stellate spicules have rather coarse rays which often 

 bifurcate, as in C. australiensis, Carter ; they measure *025 millim. 

 in diameter, the globostellates '032 millim. Having regard to the 

 nearness of the two localities, and to the points of positive agreement 

 between the present specimen and Schulze's species, I am disposed 

 to consider them to be identical. The present specimen differs from 

 0. australiensis in the relatively longer and more slender arms of 

 the stellate (radiostellate of Carter), the greater abundance of the 

 spicules in the subcortical tissues, and the larger size of both spicules 

 (in C. australiensis the globostellate measures '025, the stellate 

 about -02 millim.). 



A very small specimen, about 5 millim. across, on a Nullipore 

 which has been partly overgrown by a repent Chalina. 



Hah. Marie Louise Island, Amirante group, 16-17 fms. 



Distribution. Eed Sea (Schulze) ? 



challnltxe. 



The percentage of species of Chalinidae in this collection is small 

 for the Tropics, viz. less than 8 per cent., that of the Chalinidae in 

 the Australian collections being 15 per cent. This inferiority in 

 numbers is due in part to the absence of the tubular forms, which 

 are represented by Tuba, Siphonoehalina, and Tubulodigitus near 

 Australia, and chiefly by Tuba in the West Indies. As, however, 

 Siphonoehalina occurs both at the Cape (Ehlers) and the Red Sea 

 (British- Museum collection), it probably will be ultimately found 

 also in the intervening district. If the wide-mouthed genus Tuba 

 is really absent here, the circumstance is of considerable import- 

 ance, as it seems to be represented abundantly in the tropical parts 

 of both sides of the American continent and in the Malay archi- 



