HOLASTERELLA. 163 



the stellate spicules fill the interspaces between the rays of the larger ; they also 

 line the canals, and apparently cover the surface of the Sponge. 



Mr. Carter did not give a diagnosis of this genus apart from the characters of 

 the typical species H. conferta. I have prepared that given above from a study of 

 the type specimen described by Mr. Carter, and now in the possession of Mr. J. 

 Thomson of Glasgow ; and Mr. Carter kindly supplied me with some detached 

 fragments from it. 



The type-specimen is in a very unfavorable condition of preservation, and the 

 characters of many of its component spicules cannot be ascertained with certainty. 

 The larger spicules are so fused and intermingled together that no complete forms 

 are exposed to view ; there is no doubt, however, that some are normal hexactinellid 

 spicules, with smooth, tapering rays, whilst others, judging from fragments, are 

 peculiar forms with curved and spinous rays. The minute stellate spicules of the 

 surface, and lining the canals of the Sponge, have from six to fifteen rays radiating 

 from a thickened centre. It seems highly probable that the stellates with more 

 than six rays may be merely modified hexactinellid spicules in which furcation has 

 taken place in one or more of the normal rays. Owing to their small size, and their 

 present condition, the central portion of these spicules is not clearly shown. 



The larger spicules, which Mr. Carter has described and figured as belonging to 

 the type specimen, were not obtained from it, but they were detached spicules, and 

 it is uncertain if they were derived from the same locality as the Sponge itself. 

 Mr. Carter regarded these detached spicules (I. c, pi. xxi, figs. 4, 5, 7) as identical 

 with those forming the interior portion of the skeleton of the Sponge, but after 

 careful examination of the original specimen, I am unable to agree with this con- 

 clusion. The larger spicules in it are to a large extent concealed and obliterated ; 

 but, judging from the portions remaining, they appear to me to be quite distinct 

 from the " double stelliform nail-like spicules," originally figured by Mr. Carter as 

 doubtfully belonging to Hyalonema Smithii (' Ann. and Mag. Nat. Hist.,' ser. 5, 

 vol. i, p. 133, pi. ix, fig. 11). 



As this genus is, in part at least, composed of normal hexactinellid spicules, 

 its systematic position appears to me to be in the Lyssakine group of the 

 Hexactinellidge. Mr. Carter, however, regards it as the type of a new group, 

 ' Holasterellina,' among the Suberitida, thus belonging to his Holorhaphidota 

 (■= Monactinellidse). 



Only the typical species H. conferta can, in my opinion, properly be included 

 in the genus ; the other species which by Mr. Carter and myself (before that I had 

 seen the original specimen) have been referred to it, I propose to place in distinct 

 genera. 



