Mr. H. J. Carter on the SarcohexactinelUd Sponges. 283 



Add to this the presence of little, clear, silicilicd spheres, 

 formed of concentric layers round a minute cavity or cell, which 

 have not been mentioned in the above description of Laharia 

 because they appear to be rather accidental than normal pro- 

 ducts, receiving elucidation from a new species of Dictyocy- 

 Undrus among sponges collected by Col. Pike, U. S. C. at the 

 Mauritius, and forwarded to Prof. Dickie, of Aberdeen^ who 

 sent them on to me for examination, wherein such spheres 

 abound in all degrees of elongation, passing at last into a 

 lengthened spicule of the normal form, — thus showing that they 

 are caused by arrest of development in the original ce/Z, which 

 elongates itself normally into the entire spicule — but failing in 

 this, continues to increase in size spherically by the addition of 

 silicihed concentric layers to its surface. 



As regards the sarcospiculous hexactinellid sponges called 

 LanufjineUa pupa^ Sdt., and Aidodictyon Woodwardii, Kent, 

 respectively, I am unajble to state any thing further than that, if 

 young specimens of larger sponges, they must wait until the 

 latter are found for their fully developed specific characters, 

 while, if already adults, they have not yet been sufficiently 

 described for this. 



There is a spicule, though, in Aidodictyon Woodwardii^ Kent 

 {oj). cit. fig. 22), which, so far as my observation extends among 

 the Hexactinellidai, is peculiar to this species ; but this is 

 rather a vitreous than a sarcospiculous sponge, and belongs 

 to the Aphrocallistida3, of whicli I shall have more to say 

 hereafter. 



Sympayella mix, Sdt., too, seems to be a compound of both 

 sarcospiculous and vitreous Hexactinellidte ; for part of its 

 spicules are sheathed (like those of Euphctella aspergillimi) in 

 silicified sarcode or silicified horny substance, the rest being free. 

 Still this is only a permanent condition of what takes place in 

 all the vitreous sponges, where the spicules are formed first in the 

 sarcode free, and then enclosed in silicified sarcode or silicified 

 horny substance, as the case may be. The "3rd "form of 

 minute, equi armed, hexaradiate spicule, which I have described 

 at p. 281 as being so beautiful, I have since found to be 

 equally abimdant in SymjKigeUa, together with the 2nd or 

 capitate one ; so that, as at first thought, this is not peculiar 

 to RosseUn, and may be found to be still more common by 

 further observation*. 



* I have just found, too, in a mounted specimen, tiiat the form No. 3 

 (at p. 281 ) also exists in Crateromorpha Meyeri, but with straight capitated 

 " filaments," instead of bent ones without heads, more like Schmidt's 

 figure of that in Holtrnia PoKiialesii (' Atlantisch. Spongienfaunn,' pi. i. 

 f. (5). Crateromorpha and Rossella are very much allied in many other 

 points, which I shall mention on a future occasion. 



