IlexaotinellidtB and Lithistidge. 451 



(fig. 11, c?). An abnormal form of the rosette is to have the 

 arms continued respectively into one large ray. 



6. The same, but with the axis stretched out linearly, shaft- 

 like, and the rays arranged round it more or less spirally ; rays 

 long, spine-like, capitate, most numerous at the ends, where 

 they are more or less divergent (PI. XIII. fig. 17). 



7. The same, with the rays of the shaft more confined to 

 its centre, and all simple (that is, not capitate, but pointed). 



N.B. The last two forms are not near so abundant as the 

 globular rosette (PI. XV. fig. 11, (^). 



AphrocalUstes heatrix. 

 We now come to Aphrocallistes heatrix^ in which it will be 

 also found that, besides the common large sexradiate spicule 

 on which the vitreous structure is based, there are six other 

 kinds, viz. : — 



1. Similar to no. 1 of ^. Bocagei^ but a shorter, coarser, 

 and more robust form, spined throughout. 



2. The same as no. 2 in ^. Bocagei. 



3. A sexradiate spicule whose pointed arms are sparsely 

 and irregularly covered throughout with smooth spines curved 

 outwards, and longest about the union of the middle with the 

 inner third, diminishing towards the extremities of the arms 

 (PL XV. fig. 10). This appears to be the analogue of no. H 

 in A. Bocagei^ since I have never seen the sexradiate spicule 

 with feather-like spined arm in A. heatrix^ nor has Mr. Kent, 

 who also states this, and that the one figured in liis ilhistration 

 of this sponge is taken from Dr. Bowerbank's (P. Z. S. 1869, 

 pi. xxii. fig. 3). If, however. Dr. Bowerbank has been more 

 fortunate in this respect, his figure shows, by the abortive con- 

 dition of the spines on the feathered arm of this spicule in A. 

 heatrix compared with that in A. Bocagei^ that this spicule is 

 very poorly, and therefore perhaps very sparsely, represented 

 in A. heatrix. 



4. A scopuline spicule, consisting of a long shaft and four 

 rays ; the rays quadrangularly based on a hand-like expansion 

 o" the end of the sliaft ; for tlie most part proceeding for some 

 distance almost parallel to eacli other, when they end by be- 

 coming slightly divergent, terminating respectively in small, 

 smooth, round heads, surrounded by recurved spines. The 

 rays and the end of the shaft also microspined throughout 

 (PI. XV. fig. 2). 



5. A straight large shaft more or less beset with long, 

 thorn-like spines, most numerous towards the centre, Avhere 

 they are vertical, and at the extremities, Avhere they are diver- 

 gent ; each slightly curved and microspined (PI. XIII. fig. 20). 



