21 



The distal parts of the basalia of the root-tuft or peduncle are mostly 

 badly preserved. No peculiarities distinguishing them in any way from the 

 basalia of other Hyalonema species were noticed. 



The only specimen of Hyalonevia rapa was found in the Bay of Bengal 

 10° 12' N., 92' 30' 30" E. in a depth of 1109 m.=603 fths. 



Hyalonema martabanense F. E. Sch. 

 Plate XVIII. 



1900 Hyalonema martahnnense F- E. Sch. in Abh. Preiiss. Ak. 1900 pp. 12-15, Taf. 11. 



I have named this species after the Gulf of Martaban, the locality where it 

 was found, Hyalonema m,artabanense. Three specimens of it were captured there. 

 The one preserved best, the root-tuft or peduncle of which however has been 

 entirely torn off, has the shape of a truncated cone and is 10 cm, long. The 

 broader upper end has a diameter of 35 mm. The lateral surface of the cone 

 is considerably crushed and injured and covered with irregular depressions. 

 Below it passes into the slightly depressed basal face, above it is hmited by a 

 distinct marginal border. This divides it from the upper, laterally slightly 

 overhanging terminal plate, which has a very different structure (pi. XVIII, f. 1). 

 The terminal face is considerably depressed in the centre and raised towards 

 the margin to form a low ring-wall with sharp projecting edge. The lateral 

 surface is irregularly pitted and covered with a dermal reticulation. The termi- 

 nal face is continuous, velvety, and perforated by more or less circular, irreg- 

 ularly scattered apertures, 2-3 mm. wide, the openings of the excurrent canal- 

 stems. In one of the other, smaller specimens, which is badly preserved, much 

 compressed and worn, the same features can be recognised. The third specimen, 

 evidently a fragment, consists of a strongly-compressed, oval lamella, the size 

 of a human ear. 



The most conspicuous macrosclere parenchyraalia are the slightly curved or 

 angularly-bent, smooth and spindle-shaped oxydiactines. These can be detected 

 by'^the naked eye. They are 6-12 mm. long and 150-250 /* thick. Only excep- 

 tionally their ends are sharply pointed, usually they are more or less blunt. I 

 have found no trace of a thickening or of protuberances in the centre of the spi- 

 cule. The oxydiactines are arranged longitudinally and occur in the interior, 

 chiefly just below the dermal membrane. Very numerous similar, but smaller, 

 amphioxes are also met with. These are 400-800 M and more long, isolated, or 

 ao-gregated in strands or bundles. The latter form a network with wide meshes, 

 wTicli'traverses the sponge in all directions, the bundles parallel to the surface 

 however predominating. As in other Hyalonemas these spicules are either quite 

 smooth, or they have in the centre a slight inflation, or two opposite, or four 

 crosswise-arranged, protuberances. Sometimes, particularly frequently in the 



