HBXACTINELLIDA. 7 



curved prongs 459 /a in length. The autodermalia (IV., 2 b-b^) are hexactins (2b^), 

 pentactins (2b), and rarely stauractins (2b^), each ray being 75 x 11 /u,, wholly spined, 

 nearly cylindrical, and with blunt end. The pentactins have a well-developed distal 

 spiny knob. The hypodermalia are slender oxypentactins with paratangential rays 

 with roughened surface and with large prickles. These well-known spicules are not 

 figured owing to want of space. The autogastralia (IV., 2c) are large slender 

 hexactins, each ray being 173 x 6 fi. Some of the hexactins, a little below the 

 surface, are very large, with the radial rays (each 252 x 21 ix) longer than the 

 other four. The intermedia. — The holoxyhexasters (IV., 2d, d^), hemioxyhexasters 

 (IV., 2d^), and monoxyhexasters (IV., 2d^ 2d^), about 164 /a in diameter, have very 

 slender roughened rays, the primary rays being very short or almost absent. The 

 calycocomes (IV., 2f) are 80 /a in diameter, with long tuberculated primary rays, each 

 22 ju, in length, ending in a solid hemispherical capitulum from which the only slightly 

 divergent secondary rays proceed, presenting, as Carter put it, a dinner-fork-like aspect 

 in optical section. Another kind of calycocome (IV., 2g) has shorter, thicker, and 

 smoother primary rays, a knob-like capitulum, and more divergent secondary rays. 

 Medium-sized holodiscohexasters, like those figured by Schulze (6, pi. Iv., fig. 15) do 

 occur, but rarely. Plate IV., Fig. 2e, shows a modified hemidiscohexaster 45*5 /a in 

 diameter, having bulbous primary rays, and terminal discs little more than a circle of 

 spines. The microdiscohexasters (IV., 2h), 50 yx in diameter, have long primary rays 

 10 ju, in length, ending in a conical point, the secondary rays being given off in two 

 circles a little separated from each other. 



Scattered over the outer surface of the upper part of the specimen are numerous 

 small flattened pyriform buds about 52 ram. in length, each bud being supported on 

 one or two pleuralia which penetrate it. None of the buds are sufiiciently developed 

 to show oscule or central cavity. The hypodermal oxypentactins have their paratan- 

 gential rays much more curved than in the adult state, and the prickles are hardly at 

 all developed. The soft tissues appear much contracted by the strong spirit. A 

 section shows an outer trabecular layer surrounding a central mass of choanosome, 

 there being only a slight development of an inner trabecular layer, and that so 

 contracted as to appear solid rather than reticular. 



Specimen B.— (Plate I, fig. 2, and pi. IV., fig. 3h.) 



This is a large spheroidal sponge, 15 "5 cm. in height, with a dense velum 

 resembling a tangled thicket, extending about 1 ' 1 cm. away from the surface, and 

 with a thick root-tuft. The orifice, which is oval and with sharp angles at each end, 

 is 3 ' 7 cm. in length by 1 ' 4 cm. in its greatest breadth. 



The marginalia, projecting about 2 cm., lean towards each other across the orifice, 

 the innermost layer extending almost horizontally across from one side ; on a level 

 with the oscule is a depression, looking like a second oscule, but the appearance is due 



