90 CALYCOSILVA CANTHARELLITS. 



In view of these circumstances I consider these spirally twisted skeletal 

 elements as spicules sui generis, and the difference between them and the similar, 

 not spirally twisted spicules, as similar in nature to the difference between the 

 simply curved and spirally twisted horns of closely allied forms of Bovidae. 



The plumicotnes (Plate 2, fig. 12c; Plate 7, figs. 1-5) are quite abundant in 

 C. c. vars. simplex and helix, but exceedingly rare in C. c. var. megonychia. 

 Those of C c. var. helix are 47-55, those of C. c. var. simplex 50-69 m in diameter. 

 Those of C. c. var. megonychia seem smaller than those of the two other varieties. 

 Measurements I cannot give, because I saw only few and these were broken. 

 Four equal main-rays, which enclose angles of 90° with their neighbours, arise 

 from a slight central thickening about 2.5 m in diameter. These main-rays are 

 straight, cylindrical, smooth, 9-12 n long, 0.9-1.6 n thick, and simply rounded 

 at the end. Some distance below the end each main-ray is thickened to a spheri- 

 cal or oval tyle, 2-3 ^ in diameter. The distal part of the main-ray, lying beyond 

 this tyle, is 2-4 n long. A considerable number, twenty or more, branch-rays 

 arise from the tyle of each main-ray. Their points of origin are fairly equidistant, 

 but irregularly scattered over the surface of the tyle. The end-rays are very 

 thin and strongly curved in an S-shaped manner. They terminate with fine 

 points. A few small spines are occasionally observed on the concave side of their 

 distal part. The end-rays are equal and regularly arranged so as to diverge 

 above in a plumose manner. 



I tliink there can be no doubt about the close relationship of the sponges 

 above described. All the specimens were found at the same station; the frag- 

 ments appear to be parts of sponges similar in shape to the complete specimen; 

 no difference could be detected in their soft parts; and the shape and arrange- 

 ment of most of their spicules are the same in all. Still there are differences in 

 the spiculation of the thirty-two specimens, according to which they fall into 

 three groups. The chief differences between these groups, which I describe as 

 distinct varieties, are tabulated on p. 91. 



The nearest alhes of the sponges described above as Calycosilva cantharellus 

 are the species assigned by previous authors to the genera Sympagella, Calyco- 

 soma, and Aulascus: — Sympagella mix O. Schmidt 1870 (F. E. Schulze 1887, 

 1897, 1899, 1900; Topsent 1904); Aulascus johnstoni F. E. Schulze 1887 (F. E. 

 Schulze 1897); Calycosoma validum F. E. Schulze 1899; Sympagella anomala 

 I. Ijima 1903; and Calycosoma gracile F. E. Schulze 1903. All these, with the 

 single exception of Aulascus johnstoni F. E. Schulze differ from Calycosilva 

 cantharellus by being destitute of hypogastral pentactines. Aulascus johnstoni 



