324 



HYALONEMA (OONEMA) BIANCHORATUM PINULINA. 



In these amphidiscs the shaft is straight, regularly cylindrical, destitute of 

 a central tyle, and perfectly smooth. 



The proportion of the length of the anchors to the total length of the whole 

 spicule is in both specimens together, as stated above, 1 to 2-2.5, on an average 

 1 : 2.3. The difference between total length and anchor-length is in the small 

 macramphidiscs, in contradistinction to that of the large, on the whole the 

 greater the shorter the spicule. In the longer small macramphidiscs, over 

 180 IX in length, the above proportion is 1 to 2.2-2.3, in the shorter, under 130 ix 

 in length, 1 to 2.4-2.5. 



The terminal anchors are composed of from eight to twelve teeth. Eight 

 is the most frequent number, but small macramphidiscs with from nine to 

 twelve are by no means rare and in no way abnormal. The position of the teeth 

 of the two terminal anchors of the same spicule is alternate. The indi\'i(hial 

 teeth have a T-shaped transverse section. The upper band-shaped i)art is, 

 in its midtlle-part, 22-30 m broad and attenuated both distally and proximally 

 (Plate 82, fig. 26). It is not only longitudinally, but also transversely curved, 

 concave to the shaft (Plate 84, fig. 27), and usually rounded, very rarely pointed, 

 at the end. The keel, that is the part corresponding to the lower stroke of the 

 T, is low distally but attains a great height and thickness proximally (Plate 84, 

 figs. 26, 28, 32). The outer contour of the tooth, when seen in profile, appears 

 as a line strongly curved near the base and at the tip, but only slightly curbed 

 in its middle-part. The middle-part of this line diverges at an angle of 20-30° 

 from the shaft; its end-part is convergent to the shaft. The end-parts of the 



