76 



the curvature of the tube-wall in which they lie. The upper, longitudinal, para- 

 tangential ray, which is also pretty long (1-2 cm.) is, a short distance from the 

 centre of the spicule, strongly curved towards the axis of the sponge. These upper, 

 inwardly bent rays of the marginal principal hexactines form the lateral support 

 of the terminal sieve-plate and extend in it centripetally, following its curvature. 

 The terminal sieve-plate is surrounded by a collar only about 1 mm. high, ex- 

 tendino- obhquely upward and outward. This is composed of the distal, radial 

 rays of the sword-shaped hypodermalia occupying the upper margin of the 

 tube-wall. These spicules are here larger and stouter than elsewhere, and the 

 distal ray, taking part in the formation of the collar, is considerably elongated 

 and covered with spines. In the larger specimen these marginal hypodermal 

 hexactines are arranged in one or in several rows and their distal, collar-forming 

 rays are particularly well developed, gradually pointed, and covered with more or 

 less numerous spines, pointing outward. 



The strands of the skeletal reticulation of the terminal sieve-plate chiefly 

 consist of centrotyl oxydiactines of various sizes, which, lying parallel and close 

 together, form dense spicular fibres. In the larger specimen some of these 

 oxydiactines are slightly curved and 200 /^ and more thick. Together with 

 these spicules triactines with two long rays lying nearly in line, and one short, 

 terminally often rounded ray vertical to the other two, also occur in the 

 sieve-plate. Stauractines and— here and there in the nodes of the network— 

 hexactines, with rays of varying length, are hkewise found in it. To the thicker 

 strands, particularly of the central part of the terminal sieve-plate, dermal 

 and gastral membranes of the usual character, and a little of the parenchyme, 

 are still attached. The latter does not differ essentially in structure and spicu- 

 lation from the parenchyme of the tube-wall. 



The smaller specimen of this graceful species was found near the Laccadives 

 10' 47' 45" N. 72° 40' 20" B. in a depth of 1290 m.=705 fths. ; the larger speci- 

 men S.S.W of Cape Comorin 7° 5' 45" N. 75° 4' B.in a depth of 1316 m.=7i9 fths. 



Saccocalyx, F, E. Sch. 

 Saccocalyx pedunculata F. E. Sch. 

 Plate XIII. 



1895 Saeeocalyx pedunculata P. E. Sch. ia Abb. Preaas. Ak. 1895 pp. 53-56, Taf. V. 



When I first described this sponge in 1895 I placed it, on account of the 

 strong pinule-like developement of the hexactine dermalia in the family Asconem- 

 aiUx. Since then I have however been convinced * that its spiculation is more 

 closely alUed to that of EuplecteUids, for instance Hertwigia. 1 accordingly now 

 place Saccocalyx in the Family Euplectellidae. 



* Amerikauische Hexactinelliden 1899 pp. 96 and 98. 



