198 HYALONEMA (HYALONEMA) AGASSIZI. 



Station 3684 (A. A. 17) and Station 4740 and the other specimens from Station 

 4742 are flattened, cake-shaped. In the specimen from Station 4656 the gastral 

 cavity is a narrow fissure, uninterrupted by radial plates; in all the specimens 

 frona Stations 4651 and 4740, in the cake-shaped specimens from Station 4742, 

 and probably also in the specimen from Station 3684 (A.A. 17), the gastral cavity 

 is quite wide and divided into separate diverticula by radial plates. The dermal 

 pinules of the specimens from Stations 4656 and 4740 have longer distal rays than 

 the others. The dermal pinules of the specimen from Station 4656 and the pear- 

 shaped specimens from Station 4742 have more slender distal rays (together with 

 the spines) than the others. The spines of the distal rays of the dermal pinules 

 of the specimen from Station 3684 (A.A. 17) are more crowded and form a more 

 compact structure than those of the others. The distal rays of the gastral cone- 

 pinules are of five sizes. Those of the cake-shaped specimens from Station 4742 

 are on an average only 90.5 n long, those of the specimen from Station 4651 



98.2 n, those of the specimen from Station 3684 (A.A. 17) 106.7 m, those of the 

 specimens from Stations 4656 and 4740 128.2 ^1-128.5 n, and those of the pear- 

 shaped specimens from Station 4742 129 ^ long. Those of the specimens from 

 Station 4740 are (together with the spines) narrower than the others. The 

 microhexactines are relatively large in the specimens from Stations 4651, 4656, 

 and 4742, smaller in the specimens from Station 4740, and still smaller in the 

 specimen from Station 3684 (A.A. 17). In the specimens from Stations 4651 and 

 4740 the large macramphidiscs are of one kind and most frequently about 240 /j 

 long. In the specimens from Stations 4656 and 4742 these spicules may also 

 be said to be of one kind, and they are here most frequently about 200 m long. 

 In the specimen from Station 3684 (A.A. 17) a smaller kind, most frequently 

 about 180 IX long and a larger kind most frequently about 240 /i are nearly equally 

 abundant. The small micramphidiscs in the specimens from Stations 4656 and 

 4740 and the pear-shaped specimens from Station 4742 are most frequently about 



18.3 M long, those of the specimens from Stations 4651 and 3684 (A.A. 17) most 

 frequently about 20.1 n, and those of the cake-shaped specimens from Station 

 4742 most frequently about 22.2 m- 



This shows that the specimens of this species differ in respect to the follow- 

 ing ten accurately determinable qualities: — a, the external shape, b, the nature 

 of the gastral cavity, c, the length of the distal rays of the dermal pinules, d, the 

 maximum thickness of the distal rays, together with the spines, of the dermal pin- 

 ules, e, the density of the spinulation of the distal rays of the dermal pinules, /, 

 the length of the distal rays of the gastral cone-pinules, g, the maximum thickness 



