60 CAULOPHACUS SCHULZEI. 



Except in the vicinity of the branching points, the main- and branch-rays 

 are fairly straight. All the rays, both main and branch, are conic and gradually 

 attenuated to the end, which is 2-4 n thick. The simple stem-like basal part 

 of the branch-bearing rays is smooth. Apart from this the rays and branches 

 are entirely covered with stout, pointed, and strongly recurved spines 2-4 yu 

 long. These spines are quite uniformly scattered along the length of the rays 

 (branches) and congregated at their ends, where they form terminal verticils 

 or bunches 7-10.5 fi in transverse diameter. Particularly when viewed with 

 lower powers the terminal spine-verticils more or less resemble convex discs with 

 deeply serrated margin. The lateral spines decrease in size toward the distal 

 ends of the rays (branches). The most distally situated spines, which form the 

 terminal verticil or bunch, are much larger than the adjacent lateral ones, about 

 as large as the basal lateral ones. Exceptionally one single hypertrophic ter- 

 minal hook-like spine replaces the verticil or bunch. 



The distance of the branching point of the rays from the centrum of the 

 spicule, that is the length of the simple stem of the branch-bearing rays, is 15-22 m- 

 These stems are very short accordingly, compared to the size of the whole spicule. 

 Generally there is only one branch on a ray, but two or three are also frequently 

 met with. More than three are rare. The largest number of branches on one 

 ray observed was six. When there are more branch-rays than one, they arise 

 either at the same or at different levels. When the number of branch-rays is 

 great the latter is the rule. In most cases the main-ray is clearly distinguished 

 from the branch-ray or branch-rays by its slighter divergence from the continua- 

 tion of the axis of the stem, and by its greater length (Plate 9, fig. 21). Some- 

 times, however, there is no such distinction, the distal part of the main-ray 

 being as long and diverging as much as the branch, and the stem appearing to 

 divide into equal branches (Plate 9, fig. 18). The angle between the distal 

 part of the main-ray and the branches is variable, most frequently about 45°. 



Wilson {loc. cit., p. 48) states that in the specimens examined by him the 

 rays of the discohexactines were 80-110 ^ long and 8 n thick at the base, their 

 terminal spine-verticils or branches being 10-12 ^ in diameter and appearing 

 as watch-glass shaped end-discs. To me these groups of spines, which are 

 correctly represented in Wilson's figures (loc. cit., Plate 5, figs. 4, 5, 9), do not 

 appear as watch-glass shaped end-discs. 



The discocomes (Plate 10, figs. 15-26, 27b, 28b, 29b) normally consist of 

 six main-rays joined at right angles, each of which bears a terminal verticil or 

 bunch of end-rays. One discocome I saw had seven main-rays. The discocomes 



