304 Mr. H. J. Carter on the Hexactinellidae. 



With reference to Dr. Bowcrbank' 

 whicli he states (P. Z. S. 1869, p. 333) that Dr. Gray " is in 

 ciTor " in identifying Dactylocalyx pumiceus with D. pumicea 

 =Ipluteon higallij Bk., because " none of the singuLar and 

 beautiful forms of spicula which I have obtained from the 

 type specimen of D. pumiceus^ and have figured in plate iii., 

 part i., are to be found in the tissues of the type specimen of 

 /. Ingoing'' it unfortunately happens that figs. 9 & 10 of 

 these " singular and beautiful forms " belong to quite a dif- 

 ferent order of sponges, viz. to Pachastrella abyssi, Sdt. ; fig. 

 11 probably to a sponge of the same kind ; fig. 16 to a Gum- 

 mina, Sdt. ; and fig. 6, a & Z>, to sponges which are certainly 

 not of the sexradiate system. Thus, with the exception ^of 

 fig. 3, which (as before stated) appears to have been introduced 

 by mistake, we have nothing left here by way of illustration 

 but figures 2, 4, and 5, which are equally common to both 

 Z>. pumiceus and D. pumicea. 



With Dactylocalyx suhylobosa^ however, it is dififerent ; for 

 although two of its rosette-forms are the same as those of D. 

 pumiceus and D. pumicea^ and there is a long acerate spicule 

 present similar to that in the latter species, the large tubercles 

 with flat muricate summits respectively on the joints of the 

 reticulated stnicture in D. suhglohosa^ together with the third 

 form of rosette (viz. the pappus-like or pappiform, with straight 

 capitate rays), so far only observed in one other species 

 (viz. CrateromorpTia Meyeri)^ at once furnish the specific dis- 

 tinctions. 



Here we may shortly revert with advantage to the long, 

 linear, acerate, fusiform spicule with spined extremities, which, 

 although not seen in Dactylocalyx pumiceus^ forms such a 

 prominent feature in D. pumicea and D. suhglohosa^ that par- 

 ticular mention of it is desirable. It pierces the reticulated 

 structure of each of the two last-named sponges generally, 

 forming by its free end on their surfaces respectively a fringe 

 which, on account of the superior size of this spicule, is also 

 most noticeable in D. suhglohosa ; but although it is raicro- 

 spined towards the ends and frequently throughout, it presents 

 no circumscribed central inflation, no "cross "on the central 

 canal, nor is it ever included with the rest of the spicules in 

 the vitrified fibre, which it much exceeds in size ; so that were it 

 not so interwoven with the skeleton generally, its isolated con- 

 dition and want of sexradiate character would lead to the 

 conclusion that its presence was accidental. But what is 

 equally worthy of notice is that a similar spicule pervades in 

 a similar manner the structure of at least one of the Lithistidse 

 (viz. Azo7-ica Pfeifferoi, n. sp.), as will be seen hereafter. 



