242 HYALONEMA (HYALONEMA) GRANDANCORA. 



250 fi; thickness of shaft 13 n; diameter of central tyle 15 fi; spines of central 

 tyle 7 M long and 6 ^ thick; anchors 74 ^ long and 110 ^ broad. 



The large micramphidiscs (Plate 79, figs. 24, 25) are 37-80 ^ long, most 

 frequently about 43, 55, and 70 m-' The shaft is straight, 2-3.5 ju thick, and 

 somewhat gradually thickened in or near the middle to a stout, often rather 

 irregular, and not very clearly defined central tyle, 3-6 ^ in transverse diameter, 

 that is 1.5-3.5 m more than the adjacent parts of the shaft. The tyle and the 

 remaining parts of the shaft are quite densely covered with small, slender spines. 

 The spines on the tyle are scattered, not arranged in a verticil. 



The terminal anchors are 12-29 m long, usually a little more than a third of 

 the whole spicule, and 10.5-26 ^ broad. The proportion of anchor-length to 

 anchor-breadth is 100 to 75-100, on an average 100 : 86.3. The individual 

 anchor-teeth are strongly curved in their proximal parts and only slightly curved 

 or nearly straight in their distal and middle-parts. Their ends generally diverge 

 rather considerably from the axis of the shaft. 



The s?nall micramphidiscs (Plate 79, figs. 3-11) are 17-31 fi long, most 

 frequently about 23.3 n. The shaft is generally straight, rarely bent in the 

 middle, is 1.3-1.6 m thick, and in the larger forms often slightly and gradually 

 thickened in or near the middle, in the smaller generally of uniform thickness 

 throughout. The shaft is quite densely covered with small slender spines. 



The terminal anchors are 4-13 yu long, a quarter to a third of the whole 

 spicule, and 6-14 fi broad. The proportion of anchor-length to anchor-breadth 

 is 100 to 85-140, on an average 100 : 123. The anchor-teeth are curved more 

 strongly in their basal than in their distal part. Their ends are parallel or 

 nearly so. 



The species is very well characterized by the large size and the great relative 

 breadth of the anchors of its macramphidiscs. The only species which has 

 similar macramphidiscs and pinnies is Hijalonema (Prionema) agujanum described 

 in this Report. From this it is distinguished by the large and slender amphi- 

 discs with serrated teeth which are exceedingly abundant in H. (P.) agujanum 

 and absent in H. (H.) grandancora. 



' Their length frequency-curve has three distinct elevations corresponding to these sizes. 



