CAULOPHACUS SCHULZEI. 55 



remarks that there is no trace of a (sixth) distal ray. In the pentactines of the 

 specimens examined by me, such a trace occurs as a short continuation of the 

 axial thread of the proximal ray beyond the centrum. The measurements 

 given by Wilson {loc. cit., p. 47) are: — lateral rays 0.4-0.75 mm. by 36-48 m, 

 proximal ray 0.78-1 nmi. by 50-60 m- In his drawing (loc. cit., Plate 4, fig. 9) 

 of a pentaetine the spines are much smaller than in the pentactines examined by 

 me vdth. distinctly spined proximal ray (Plate 8, figs. 5, 7, 16, 17). 



The pinnies (Plate 11, figs. 1-16, 17a) are nearly always regularly hexactine. 

 Only exceptionally a pinule with a rudimentary proximal ray or some other 

 abnormity is met with. Apart from certain differences in their dimensions, 

 which will be dealt with below, the dermal pinules of the upper part of the stalk, 

 the dermal pinules of the body, and the gastral pinules are identical. The 

 lower parts of the stalks at my disposal are denuded of their pinules, so that I 

 am unable to say what these may be Uke. Probably they are similar to those 

 of the upper part of the stalk, but smaller. 



The distal pinule-ray is straight, 140-390 fi long, and 8-23 ^ thick at the 

 base. Above the ray thickens, and it attains its maximum transverse diameter 

 a httle below the middle of its length, where it is usually a third to twice as thick 

 as at the base. In four pinules measured, the thickness of the distal ray was: — • 



at the base 14, at the thickest point 25 /x 

 " " " 16, " " " " 28 m 



" " " 18, " " " "28 m 



" " " 20, " " " " 35 m 



Beyond the thickest place it is attenuated, at first slowly, then rapidly, to a 

 rather sharp point. It consequently appears spindle-shaped. It is covered 

 throughout with sharp-pointed, conic spines. The proximal spines are very 

 small. Farther up they become larger and they increase in size to the middle 

 of the ray, where they measure 18-22 m by 5-8 m- From here onwards they 

 again become smaller, but only ^'ery sUghtly, the uppermost spines still being 

 quite large. The proximal spines arise vertically, those farther up obUquely, 

 and the nearer we approach the middle of the ray the more inclined towards 

 its tip do their basal parts become. The small proximal spines are straight, 

 those farther up slightly curved towards the tip of the ray. The maximum thick- 

 ness of the distal ray, together with its spines, is 25-70 m- 



The proximal ray is, when normally developed, straight, 70-145 m long, 

 8-17 M thick at the base, and attenuated towards the blunt end, at first gradually. 



