80 



Their rays are about 4' tliick, straight and terminally rounded or bluntly 

 pointed. Sometimes rudiments of one or both of the missing rays of the ideal 

 hexactine are met with in the shape of rounded tubercles or stumps. Also 

 here one occasionally sees a pentactine with proximal, radial ray between the 

 ordinary stauractines. 



The gastral membrane contains numerous hexactine autogastralia, 120-140 /» 

 in diameter, with pretty gradually pointed rays, covered with small spines or 

 thorns (pi. XIV, f. 8). The spines are in these spicules longer than in the auto- 

 dermalia and often, particularly on the distal, radial ray, not quite vertical but 

 ■slightly oblique and directed outward. 



The very numerous microsclere parenchymalia are strong, rough oxyhexasters, 

 hemioxyhexasters and oxyhexactines measuring about 150 /^ in diameter. In the 

 oxyhexasters each one of the six short and smooth or slightly rough main-rays 

 is usually divided into two pretty strongly diverging, straight and gradually 

 pointed, long, rough or finely spined branch-rays (pi. XIV, f. 10]. Sometimes 

 one of the main-rays remains undivided, such main-rays being, in their terminal 

 part, similar to the branch -rays (pi. XIV, f. 9). Sometimes more than one main- 

 ray or even all main-rays remain thus undivided. In the former case these 

 spicules are hemioxyhexasters, in the latter case oxyhexactines. True oxyhexac- 

 tines are not numerous but they can be found everywhere between the oxyhexas- 

 ters and hemioxyhexasters and have the same characters as these. 



Bathydorus levis has been found in the South-western part of the Bay of 

 • Bengal 9° 34' N. 85° 4315" E. on globigerina-ooze in a depth of 3652 m,=i997 

 fths. 



Placopegma F. E. Sch. 

 Plaeopegraa solutum F. B. Sch. 

 , Plate XIV figs. 11-17. 



1895 Placopegvna solutum F. E Sch. in Abh. Preuas. Ak. 1895 pp. 63-65, Taf. VI, figs. 11-17. 



Only the upper part, of a single specimen, the size of a hen's egg, is con- 

 tained in the " Investigator " collection. This has a loose texture and possesses a 

 large oscule, covered by a sieve-plate which gives to the sponge a peculiar and 

 characteristic appearance (pi. XIV, f. 11). 



The body consists of an irregular network of thin lamellae, inclosino- lacu- 

 nous cavities of various size, local extensions of the in- and excurrent canalsys- 

 tem. A large gastral cavity, irregular in shape, into which the excurrent canals 

 open, lies underneath the sieve-plate. Below the dermal membrane, which is 

 unfortunately badly preserved, an irregular labyrinth of incurrent, subdermal 

 cavities extends. 



