218 Mr. II. J. Carter on 



GkaHna polychotoma, Esper, = Ghalina oculata, Bk., such 

 is the tendency, as before stated, of the sponge-sarcode 

 throughout the class to produce the same kind ot' forms 

 whatever the composition may be; so that here, although the 

 form is like that of a caulescent ( 'halma, the characteristic 

 toughness and resiliency of the latter, which arises from the 

 presence of a large amount o( keratine, is absent in Dysidea 

 chaliniformisy where the opposite state renders it so brittle 

 that, when wet, it is almost impossible to handle the specimen 

 without a piece coming off, and in drying it breaks down 

 under the slightest force. 



There is another chaliniform specimen in the collection, 

 but here the increased development of keratine, oi which the 

 lateral fibre is exclusively composed, not only lessens the 

 amount of brittleness, but necessitates its being relegated to 

 another genus, in which it will be found hereafter. 



Let us pause here for a moment and revert to the " tabular 

 view" which 1 have inserted at p. 215, in which it will be 

 observed that the third and last family o\' the P8A.MMONEMATA 

 is termed " Pseudohircinida," of which it may be simply 

 stated here that, not being intended for the genuine species o\' 

 the order, its consideration may be postponed for a more con- 

 venient opportunity ; meanwhile to proceed with our revision, 

 I find it also desirable to suppress the fifteenth group in my 

 original classification, viz. the Sarcocornea, and its present 

 diagnosis altogether) and make it a genus in the sixteenth 

 group, viz. the Arenosa, under the diagnosis just mentioned. 

 Thus we should have three genera in the group "Arenosa ; " 

 but, inasmuch as further alterations will presently show that 

 these sponges should have a distinct family name, 1 would 

 propose for this the term " Arenida," when the whole would 

 stand as follows : — 



Family. Group. Genera. 



{1. Holopsumma. 

 2. Sarcocornea. 

 ::. Dysidea. 



We now come to Psammonematous sponges in which part 

 of the fibre only is cored or axiated with foreign material, 

 the other part being clear, that is, composed of keratine only, 

 the former belonging to the vertical and the latter to the 

 lateral, which is merely an extension laterally of the vertical 

 fibre in an exclusively keratose state, as it is almost exclu- 



