APHKOCALLISTES FROM THE DEEP SEA. 325 



ApJirocallistes Bocagei, Q. J. Micr. Sci. 1870, p. 4. Fistulous 

 branching sponge.) 



Carter, enlarging on the diagnosis, gives a careful description 

 of the species (Quart. Journ. Micr. Sci. vol. xii. p. 450). He 

 notices that, besides tbe common large sexradiate spicula on which 

 the vitreous structure is based, there are several other kinds, all 

 of which are more or less free from the vitreous mass. Of these, 

 the brush-spicule, and the rosette with three rays to each arm, 

 are common in the specimen under consideration, and the scopu- 

 line spicula also. 



The form under consideration is a young one and not a frac- 

 tured old one. At one spot on tbe free edge the process of mesh- 

 making can be well seen to be due, both to the collection of silica 

 around previously existing hexactinellid or quinqueradiate spicula, 

 and also to the growth of irregular siliceous threads in tbe sarcode, 

 irrespectively of any geometrical form. The dermal spicula differ 

 in many points from those which have been published as character- 

 istic of ApJirocallistes, but some of the normal kinds are present. 



Derm. — Very slender, long-rayed, hexactinellid spicula. Tbe 

 stem is as slender as the rays, but is shorter and straight. The 

 rays are very slender, uniform in thickness, slightly bent, and 

 long. At the junction is a slight swelling, and the prolongation 

 of the axis is short and rounded off in a blunt spear-point. Sarcode 

 adheres to the spicula, and extends between the rays. 



The arms are separate from those of neighbouring spicula, 

 or are under them, forming a discontinuous network (Plate 

 XXV. fig. 2). These spicula are very numerous, and are found 

 crowding the outside of the main skeleton and the derm which 

 covered up the interstices. Often the vertical limb stands on the 

 siliceous continuous skeleton, and the four at right angles to it 

 then extend on all sides. 



Slender, moderately long-rayed, hexactinellid spicula — the axial 

 ray very long, above and below the plane of the others, in one 

 direction slightly curved, and jagged on the edge (Plate XXV. 

 fig. 3). Small hexactinellid spicula — the axis on one side of the 

 plane of the radii, minutely ascendingly spinulose (Plate XXV. 

 fig. 7). Others with the spinules standing out at right angles to 

 the axial ray, and very minutely rugose about the rays also 

 (Plate XXV. figs. 4 and 5). Moderate-sized hexactinellids — the 

 radii stout and attenuating, and one of the axial rays also ; the 

 others slightly shorter, and closely but sparely spinulate in whorls, 



