66 



distal rays are covered with short spines for the greater part of their length, 

 frequently right down to the vicinity of the centre of the spicule. To this distal, 

 radial, free ray rough, oxydiactine comitalia with a well defined, central, knot- 

 shaped thickening are sometimes closely attached longitudinally. Generally 

 however a typical floricom adheres to the pointed and roughened end of this 

 distal ray. The floricoms measure 80-100 H- in diameter and bear 7-8 branch- 

 rays on each main-ray. The branch-rays terminate in not sharply defined 

 terminal discs, curved in a hand-like manner, with about 7 small, marginal teeth 

 (pi. XXII, f. 3, 4). 



The hypogastralia are always simple, smooth oxypentactines with a more or 

 less elongated, radial and four equal basal rays, lying tangentially in the gastral 

 membrane. Their length and thickness is subject to considerable variations. 



The oxypentactine canalaria are similar in shape and position but not so 

 large. These spicules not infrequently have a sixth ray which protrudes into the 

 cavity of the canal, in which case they must, although this sixth ray is quite 

 short, be considered as hexactines. 



The hypogastralia of the iris-like membranes surrounding the parietal aper- 

 tures are v.ery peculiarly developed. They are here converted into stout pentactines 

 or hexactines with short, thick and equal, conical rays only about 100 /* long (pi. 

 XXII, f. 1). Also on the margins of the meshes of the terminal sieve-plate such 

 pentactines and hexactines with short, strongly thickened, conic rays are met 

 with. On the whole however the sieve-plate resembles the other parts of the 

 body, both in the structure of its soft parts and its spiculation. 



The basalia-spicules, of the root- tuft do not essentially differ from those of 

 most of the Euplectella species. The well-known club-shaped anchors with several 

 (5-12) smooth, recurved teeth are mumerous (pi. XXII, f. 9), but I have not 

 been able to find the simple pentactine-anchors with axial canals in the four trans- 

 verse rays, which occur in Euplectella aspergillum and E. simplex. 



The Indian Euplectella regalis F. E. Sch. accordingly appears to be most 

 closely related to the Japanese Euplectella imperialis Ijima, of which Ijima 

 recently has published a detailed description in the Journal of the College of 

 Science, Imperial University, Tokyo, Japan, Vol. XV, p. 59. The chief differ- 

 ences between the two are the following. All the large specimens of Euplectella 

 imperialis are slightly bent in the central part of the body, the only known, 

 doubtless full-grown specimen of Euplectella regalis is on the other hand quite 

 straight. The stout and strong spicules of the iris-like annular membranes 

 which surround the parietal apertures are hexactine in Euplectella imperialis, and 

 mostly pentactine in Euplectella regalis. In the parenchyme of Euplectella 

 imperialis numerous graphiocoms (graphiohexasters) are met with, in Euplectella 

 regalis these spicules are absent. 



