326 



HYALONEMA (OONEMA) BIANCHORATUM PINULINA. 



The chief dimensions of the sjjiall micramphidiscs (Plate 84, figs. 15-25) 

 are: — 



In these amphidiscs the shaft is usually straight, rarely curved. In some 

 place at or near the middle it is thickened, gradually in the larger, more abruptly 

 in the smaller, to a rather stout central tyle. In the larger forms the tyle and the 

 adjacent parts of the shaft, about one third of its total length, are densely cov- 

 ered with spines sometimes 1 ^ long. The end-parts of the shaft of these am- 

 phidiscs are smooth or only roughened by exceedingly minute spines. In the 

 smaller forms the spines on the shaft are so small that they can hardly be made 

 out as such, and merely render the shaft somewhat rough in appearance. 



The anchor-teeth are curved rather strongly in their proximal part, l^ut 

 only slightly or not at all in their distal part. Their end-parts are generally 

 slightly divergent. 



A few abnormal small micramphidiscs were found in specimen 6. In one 

 of these, 26 m long, a straight cylindrical branch arises very obliquely from 

 the shaft. This branch is as thick (1.6 m) and half as long as the shaft, and 

 broken off at the end. In another small micramphidisc (45 /z long, with termi- 

 nal anchors 19 m long and 22 /.i broad), two opposite rays lying in the same 

 straight line and both vertical to the shaft arise from the centrum of the spi- 

 cule. These rays are straight, as thick as the shaft (2 m), and, like the shaft, 



