HEXACTINELLA. 149 



draw the same conclusion as I should concerning then- origin from this com- 

 parability and their general structure, and expresses ^ his inclination to consider 

 them "as diacts or monacts." 



In spite of the fragmentary condition of the specimens they can, with a 

 sufficient degree of certainty, be assigned to Hexactinella. Of all the known 

 species only two, H. ventilabrum Carter and H. labyrinthica Wilson, have, like 

 them, discohexastrose microscleres. From both of these species the sponge 

 above described differs by the scopules, which have four end-rays in the former, 

 and usually seven end-rays in the latter. 



Hexactinella sp. indet. 

 Plate 32, figs. 13-15. 



A skeleton-net probably a species of Hexactinella was trawled off the south- 

 ern coast of western Panama at Station 4631, on 3 November, 1904; 6° 26' N., 

 81° 49' W.; depth 1415 m. (774 f.); they grew on a bottom of green sand; the 

 bottom-temperature was 38°. 



This skeleton-net (Plate 32, fig. 13) has the shape of a funnel 30 mm. high 

 and 52 mm. in maximum breadth above. The funnel-wall is 4 mm. thick. 

 Both the upper marginal part and the lower end, which latter may have been 

 attached to a stalk, are broken off. The funnel-wall consists of skeleton-net 

 lamellae extending radially and longitudinally from the base towards the margin. 

 These lamellae are mostly a little over 1 mm. apart and joined to each other by 

 groups of oblique beams, which, on the inner side of the funnel, form a honey- 

 comb-like net (Plate 32, fig. 15) composed of lamellae vertical to the surface 

 and enclosing short, Ukewise vertical canals, round or polygonal in transverse 

 section, and mostly 1.5-2.5 mm. wide. 



The skeleton-net of these lamellae consists of smooth beams, on an average 

 about 100 M thick, which in some places extend longitudinally and transversely 

 with rather large square, rectangular meshes, but which are generally, particu- 

 larly in the inner honeycomb zone, so variable in theii- dii'ection, so crowded, 

 and joined at so frequent intervals, that they form a quite irregular and very 

 dense network. 



' F. E. Schulzc. Loc. cil., p. 35. 



