218 



HYALONEMA (HYALONEMA) PLACUNA. 



whole spicule, and 0-11 n broad. The proportion of their length to their breadth 

 is 100 to 50-56, on an average 100 : 52.3. The individual teeth arise vertically 

 from the shaft, and are strongly bent in their proximal, and fairly straight in their 

 distal part. Their straight end-parts are usually parallel to the shaft. 



In form A these spicules (Plate 63, fig. 42) are similar in shape, but smaller 

 and provided with somewhat narrower anchors. Their dimensions are here 

 the following: — total length 28-38 m; length of terminal anchors 12-15 m; 

 breadth of terminal anchors 6-6.5 n; proportion of anchor-length to anchor- 

 breadth 100 to 43-50, on an average 100 : 47.5. 



The 'small micramphidiscs with broad anchors are abundant. Those of form B 

 (Plate 63, figs. 37-41; Plate 65, fig. 13) are 18.5-42 ^ long, most frequently 

 26-32 IX. The shaft is straight, 0.6-1 fi thick, and either simple and cylindrical 

 throughout (Plate 65, fig. 13) or thickened somewhere near the middle to a 

 central tyle 1-1.3 /i in diameter. This tyle and the middle-part of the shaft 

 usually bear some minute low and broad spines, either on all sides or on one side 

 only. The anchors are 6-16 n long, a little less than a third to two fifths of 



' Only one observed. " Apparently absent. ' Only three observed. 



