288 THE VOYAGE OF H.M.S. CHALLENGER. 



Lut exhibit more frequently than in the latter remnants of the atrophied sixth ray, 

 persisting in the form of a protruding, rounded, more or less elongated distal tubercle. 

 They also differ in the strong development of rounded lateral teeth on the four tangential 

 rays (PI. LXXV. fig. 8). 



Very unique and characteristic of this species are most of the dermal clavulse, of 

 which the common form in Farrea occa has only an isolated occurrence. Two pre- 

 dominant forms occur, of which one exhibits a thick, short, superiorly rounded head 

 with a central terminal jjapilla, bearing two j^arallel circlets of teeth (PL LXXV. fig. 3), 

 while the other has a perfectly smooth, long, club-shaped distal end, which is not in any 

 way sharply marked off from the stalk (PL LXXV. figs. 2, 5). These two forms of 

 clavulse are either quite irregularly distributed beside one another, or are distinctly 

 restricted to certain regions of the sponge body, or finally disposed in alternate bundles 

 in the manner represented in PI. LXXV. fig. 2. 



The strong pentacts of the gastral skeleton are distinguished by the large blunt 

 remnant of the atrophied sixth ray and also by the specially large and distant teeth on 

 the tangential rays. These teeth are not conical but rather cylindrical, and are rounded 

 ofi" at their ends (PI. LXXV. fig. 8). The gastral clavulaj are all developed in anchor 

 form, and usually possess only four strongly recurved long and narrow anchor teeth 

 (PI. LXXV. fig. 4). 



Corresponding to the strong development of the wall in the still preserved portion of 

 the single specimen captured, cross sections reveal a deep folding of the chamber layer. 

 The single chambers are somewhat smaller and more irregular than in the tube of Farrea 

 occa (PL LXXV. fig. 2), nor did the latter exhibit an equal strength of development. 



Farrea sp. (?) (PL LXXVL figs. 4, 5). 



Among numerous macerated Farrea skeletons in the Challenger collection, which 

 could not be satisfactorily identified in the absence of all isolated spicules, there was one 

 fijrm which, though small and crumbling, seemed worthy of more notice than could of 

 course be given to the majority. This specimen, which is figured in PL LXXVL fig. 4, 

 essentially differs in its whole configuration from any of the hitherto here described 

 species of Farrea. It has the form of a slightly convex funnel, somewhat broken at the 

 sides, and 1 to Ig cm. in height. It consists of a single lattice-work layer with well- 

 developed rectangular meshes, and with strongly developed beams which resemble those 

 of the dictyonal framework in undoubted species of Farrea. I would not give so much 

 attention to this form, if Carter and Bowerbank had not previously described and figured 

 as species of Farrea certain funnel-shaped Hexactinellids, of which it is possible that 

 some belong to the genus, though diflering from the tubular type in more respects than 

 in form. These forms are Farrea infundibuliformis, Carter (identical with Farrea 



