1881.] THE SURVEY OF H. M.S. 'ALERT.' 137 



spicules, whose sagittal rays lie between the radial canals, and whose 

 lateral rays serve to enclose them. The cloacal surface is formed of 

 a layer of mingled small and larger quadriradiate spicules. 



Acerate Spicules. Straight, surface minutely rough, tapering to 

 sharp points from the centre. Average maximum size 2-1 by -09.5 

 millim., extending from just beneath the cloacal to about one fourth 

 of their length beyond dermal surface. 



Stout Triradiates. Sagittal rays straight, surface slightly 

 roughened, tapering to approximately sharp points from the base, 

 forming three angles of about 120° each. Size of rays varying (ave- 

 rage maximum size) : basal from -304 by '04434 millim. to -424 

 by -05067, laterals from -2217 by -0.38 to -3167 by -04434—1116 

 proportion between the lengths of the two being thus 5 : 3 or 

 4 : 3. The basal ray is generally parallel to the long axis of the 

 sponge, while one of the laterals projects from the dermal surface. 



Slender Triradiates. Rays smooth, tapering from base to sharp 

 points ; the basal ray straight, the laterals either straight, or curving 

 slightly forwards, or slightly undulating ; the inwardly facing laterals 

 form an oral angle of from 160° to 180° with each other ; the basal 

 points outwards ; lateral angles equal. Size of rays varying (averao-e 

 maxim.um size): basal from -38 by -019 millim. to -3'! 67 by -019, 

 laterals from -152 by -0158 to -139 by '158 ; the proportion between 

 the lengths of the rays is therefore .5 : 2 or 7 : 3. 



Quadriradiates. Rays smooth, tapering from base to sharp 

 points; basal straight, laterals slightly curved, either to or from 

 cloacal surface, forming au oral angle of from 1 30° to 1 70'. Apical 

 ray straight, projecting into cloaca. Size of laterals almost con- 

 stant ; apicals and basals vary inversely in length with each other. 

 Basal ray either about -285 by -019 m'illim., or -04434 by -0095; 

 laterals (average maximum) -08235 by -0095 to -101 by -01267; 

 apical either -019 or -0507 by -006334. 



Examined. In spirit and by sections mounted in balsam. 



Hab. Victoria Bank (off S.E. Brazil), 39 fathoms ; bottom, dead 

 coral. 



Obs. The species is represented by a single specimen 10 millims. 

 long by 5-5 in extreme breadth. The projection of the points of the 

 acerate and stout triradiate spicules from the surface is disguised to 

 some extent by an aggregation between them of a yellowish material, 

 which appears to be the result of desquamation of the surface tissues. 

 This species vesemhlcs Leucandra cyathus, Verrill', from Casco Bay, 

 U.S., in its spicule-characters, and differs from all the species 

 assigned to Sycandra in the ' Kalkschwamme ' of Hiickel by the 

 possession of a cortical layer of triradiates with rays at least twice as 

 stout as those of the triradiates forming the main substance of the 

 sponge. 



1 Proc. Amer. Assoc. Adv. Science for 1873, p. 392, 



