18 



Although we know nothing of its missing basal part, we can now, taking 

 into consideration the facts stated above, endeavour to ascertain the systematic 

 position of this sponge. First, we will have to decide whether it is to be placed 

 in one or other of the genera of Hyalo7iematidse already known, or whether a 

 new genias should be established for it. Neither the shape of the sponge nor 

 . its spiculation would warrant us in adopting the latter course, and so it only 

 remains to find out which of the five known genera Pheronema, PoUopogon, 

 Hyalonema, Lopho])}illsema, and Semperella it belongs to. The lamellar form and 

 the absence of uncinates show that it is not a Pheronema, PoUopogon, Lophophy- 

 sema or Semperella, so that it must be a Hyalonema. And indeed we find that 

 the entire spiculation, particularly the parenchymal oxyhexactines with their 

 curved rays and the peculiar arrangement of the mesamphidiscs, are in complete 

 accordance with what we meet with in the other species of Hyalonema. 



The lamella must of course be considered as an upper portion of the wall 

 of a calyculate sponge. Its being so sharply folded and its upper margin being 

 so very oblique and so different from the usual circular shape, are the only points 

 which might raise doubts as to the correctness of this assumption. But it seems 

 to me that these peculiarities, even supposing them not to be mere individual 

 abnormities, cannot be considered of sufl&cient importance to exclude this species 

 from the genus Hyalonema, and the less so as one of these peculiarities, the ob- 

 liqueness of the upper margin, is met with also in some other Hyalonemas, where 

 it may, as in the Japanese Hyalonema refiexum, recently described by Ijima, be 

 extremely marked. 



The hand-high fragment was, as already stated, captured south-west of Cape 

 Comorin T 17' 30" N., 76° 54' 30" E., in a depth of 787 m. = 430 fths. The other, 

 smaller, strongly compressed fragments with irregular torn margin were also 

 found south-west of Cape Comorin T 34' 80" N., 76° 8' 23" B., in a depth of 1530 

 m.-=836 fths. 



Hyalonema rapa F. E. Sch. 

 Plate XVII. 



1900 Byalonema rapa P. E. Soh. in Abh. Preuss. Ak. 1900 pp. 15-19, Taf. I. 



Of this species there was only a single fairly well preserved specimen among 

 the " Investigator" sponges. Its body is slender, conical and pretty tough. It is 

 70 cm. long, and at the upper, truncated end, 3 cm. broad. From the lower attenu- 

 ated end a somewhat spirally twisted root- tuft or peduncle, 17 cm. long and 5 mm. 

 thick protrudes. This peduncle is composed of 20-80 spicules which slightly 

 diverge below. The spicules are a little under 1 mm. thick. The upper, ter- 

 minal face is not surrounded by a prominent edge ; its margin is rounded off and 



