EEPOET ON THE MONAXONIDA. 155 



being strengthened in this opinion by the fact that both came from the Cape of Good 

 Hope. 



The spiculation given by Vosmaer is as follows: — "Spic. tr. ac. f. (tr". ac. f.). tr. ac. 

 sp. (strongly spined). acl (rare), tr^ A (sp.) ^^. anc"." He says also — "The sponge, 

 which in the dried state is pure white, is rather elastic on account of the keratode-fibre. 

 It forms more or less flat, branching lobes. Very characteristic for this species are the 

 bows, the ends of which are spined . . . The anchors are small but rather stout, few in 

 number. The spines of the tr. ac. sp. are very strong and bend towards the blunt end of 

 the spicule. In the formula, I have designated with a --^ the small spicules which are 

 often almost bent into a circle. I could not distinctly see whether the ends are blunt or 

 pointed." We are pretty safe in eliminating the "acl (rare)" either as foreign or 

 abnormal, while the spicules designated with a ^<-^ are almost certainly Diatom rings, 

 which often occur abundantly as foreign bodies in sponge preparations ; the presence of a 

 trl is perhaps a more serious difficulty; the large, smooth styli of the two sponges 

 agree in being fusiform. It is the external appearance and the peculiar and 

 very characteristic form of the sjjiued styli and toxa in both sponges which induce 

 us to put them in the same species, at any rate as a temporary arrangement. It 

 is very unfortunate that Vosmaer has given no spicular measurements and no 

 account of the arrangement of the skeleton ; when these are known it will be much 

 easier to arrive at a definite conclusion. The presence of the distinct tufts of slender 

 stylote spicules at the ends of the primary fibres, forming a dermal crust, obliges us to 

 place this species in the genus Rhaphidophlus rather than in the genus CJathria, 

 though, as we have already had occasion to point out, the distinction is one of degree 

 rather than of kind. 



Locality. — Simon's Bay, Cape of Good Hope; depth, 10 to 20 fathoms. One specimen. 



Genus Plumohalichondria, Carter (Pis. XXX., XLVIL). 



1876. PlmnoluiKchondria, Carter, Ann. and Mag. Nat. Hist., ser. 4, vol. xviii. p. 236. 



The skeleton is arranged in plume-like columns (PI. XLVIL fig. 4a). Megasclera 

 oxea and styli ; no special kind of dermal spicule. Microsclera isochelee. 



In his paper on the Classification of the Spongida^ Mr. Carter founds a group of the 

 "Ectyonida," under the name " Plumohalichondrina," in the following passage: — 

 " Group 2. PlumohalicJiondrina. Here there are two forms of axial spicules, viz. — 

 1, simple acuate, smooth or spined ; 2, more or less pointed or inflated at the ends, which 

 are often microspined scantily or sparsely. Echinating spicule club-shaped and spined. 

 Flesh-spicule for the most part that termed by Dr. Bowerbank 'angulate equianchorate' 

 (that is, with bow-shaped shaft and alajform arms), sometimes accompanied by a 



1 Ann. and Mag. Nat. Hist., ser. 4, vol. xv. p. 144. 



