98 



THE SPONGES. 



The smooth spiral axis exhibits in projection one or two concavities on 

 same side. Axis sometimes appears cylindrical, more often is flattened 

 and band-like. Kays are minutely roughened, minutely tylote, numerous 

 and closely set along the axis. Total length of spicule, 30-40 /x ; ray 



length, 12-16 p. 



Forms occur with fewer and longer rays than the typical spicules. In 

 such forms noticeable gaps are left along the axis between the bases of 

 the rays. The rays may become conspicuously few and long, as in the 

 spicule shown in Fig. 1 e, Plate 13, where the ray length is 18-20 ^ 

 and the total length 44 jh. 



The spirasters with few rays pass into metasters of an amphiaster 

 character, the spicule bearing a few rays at each end of the axis and 

 one or two rays at about the middle of the axis. Such spicules are 



infrequent. 



The spirasters of this species closely resemble those of Thenea echinata. 





Thenea pyriformis, sp. nov. 



Plate J 3, Figs. 5, 8, 10, 11. 



Diagnosis. Body pyriforra, with a ring of inconspicuous marginal pore areas. On the 

 upper surface, a shallow oscular depression. Under surface bears numerous small conulose 

 eminences, which point downward. Surface in general feebly hispid. Megascleres : 

 Dichotriaenes, protriaenes, anatriaenes, oxeas. Micro scleres : Plesiasters ; rays, 40-60 /x 

 x 4-5 /x. Metasters of varying shape ; axis in the characteristic forms short and thick ; 

 spicule length, 28-30 /x ; ray length, 10-12 /x. 



Station SJflh 1 specimen. 



The body is pyriform in shape (Fig. 5, Plate 13), but compressed 

 in one of the horizontal axes; 27 mm. high, 23 mm. wide in one horizontal 

 axis and 15 mm. wide in the other. There is an irregular ring of separate 

 pore areas, five in number, nearer the upper larger end of the body, but 

 not all at the same level. The upper surface bears a single wide and 

 very shallow oscular depression (Fig. 8, Plate 13), which is somewhat 

 excentrically placed. This depression appears as a smooth collenchymatous 

 area, which includes the apertures of several efferent canals, and which is 

 without a special spicular fringe except at one point, where the elsewhere 

 indistinct margin forms a projection from which some spicules extend 

 obliquely 2-4 mm. over the oscular area. 



