148 Triassic Echinoderms of Bakony. 
distinguished as adapical and adoral, those terms are no longer applicable to the 
two faces of the blade. 
For descriptive purposes the distal margin of the blade may be termed North. 
Then, whether one be looking at the inner or outer face, the five other sides of 
the hexagon may be termed NE., SE., S., SW., and NW., respectively. 
The outline of the blade forms a hexagon with curved sides, having an 
extreme width of 20-4 mm., and a N—S diameter in the median line (i. e. length) 
of 9:1 mm. The S. side measures 13°56 mm. from angle to angle; it is convexly 
curved with a very slight reéntrant curve towards the middle line of the handle. 
This line is not in the sagittal plane of the blade, but about 0°25 mm. nearer to 
the SSE. angle of the outer face. 
N N 
NW NE 
SW Sey SE 
S S 
From outer side. From inner side. 
Text-fig. 17. Anaulocidaris testudo, trulliform radiole 
The N. side from angle to angle measures 12°3 mm.; it has a concave curve 
corresponding to the convexity of the S. side, but more pronounced, and with a 
median elevation corresponding to the depression in the latter. Viewed from the 
outer face, the NE. and NW. sides are convexly curved, the NE. measuring about 
51 mm., the NW. about 5°6 mm.; the SE. and SW. sides are concave, but the 
curve is less than in the NE. and NW. sides; the SE. side measures about 5°38 mm., 
the SW. side about 5°8 mm. Corresponding with the greater length of the western 
sides, the line joining the NNW. and SSW. angles (9°1 mm.) is greater than that 
joining the NNE. and SSE. angles (85 mm.). The asymmetry then consists in 
the slightly greater extent of the left side (W. as seen from the outer face). There 
does not, however, appear to be any difference in thickness, since the thickness 
measured along the lines joining NNE. to SSE., and NNW. to SSW. is 1°6 mm. 
for both sides. These lines of measurement are hereinafter designated as +—y (see 
text-fig. 19). 
The outer face is slightly convex, with the following modificatios: 1. a slight 
sinking towards the distal margin in the space between the NNE. and NNW. 
angles; in other words the surface is most elevated along lines joining the middle 
of the S. side to those angles, and these elevations, scarcely perceptible to the eye, 
represent the ridges of A. Buchi; 2. a well-marked bevel along the SW. and SE. 
sides, with a maximum width of 0°9 mm. in the plane of the blade, and of 1°5 mm. 
in the plane of the bevel; 3. a slighter bevel, at a sharper angle, along the S. 
margin; this thins out as it approaches the central depression. 
The inner face N. of the handle is gently concave, but the concavity is less 
regular than the convexity of the outer face. The main modifications are: 1. a well- 
marked bevel on the distal margin between the NNW. and NNE. angles; this 
follows the curve of that margin to some extent, but is narrower in the median 
line, where its width is 1°0 mm. in the plane of the blade, and 1°35 mm. in the 
