CARADOCIAN CYSTIDEA FROM GIRVAN. 



409 



5 213. In fundamental structure and in number of marginals, the frame seems to 

 aoree with that of C. Elizae. There is, however, no evidence for a long toe-spine in 

 any of the specimens, though there is a short thick process (ca. 3 mm. by 1'5 mm.) in 

 G5, and traces of a similar structure in G33. This process, however, seems to consist 

 not so much of the spine itself as of the two branches, which are here brought close 

 together (PI. IV. fig. 42). The knobs also are different : that on marginal 6, at the 

 ball of the foot, is stout but short, and in G2 and G33 (PI. IV. figs. 40, 41) is truncated 

 by an apparently circular, flat or faintly concave surface of 3*4 mm. and 2 mm. diameter 

 respectively. In these specimens there seems to have been a short but more pointed 

 knob on marginal 3(X, and a slight thickening, scarcely a knob, on marginal 3 at the 



heel 



toe-spine 



ball of foot 



heel 



Fig. 24.— Reverse. Fig. 25.— Obverse. 



Text-figs. 24, 25. — Cothurnocystis curvata. 

 Reconstructions of the two faces. The outline is based on the holotype and drawn twice the natural size (cf. PI. IV. 

 figs. 39, 40), but various details are filled in from other specimens. The numbers 1-11 refer to the adjacent marginals. 

 The proximal and median regions of the stem are drawn, and some elements of the distal region. 

 Fig. 24.— The reverse face, showing the strut, the knobs on 3 and 6, and the flattened plates of the integument. 

 Fig. 25.— The obverse face, showing the vent directed towards marginal 10, the subvective system stretching from stem to toe, 

 and the finely plated integument. Note how this last is stretched by the subvective system ; also how it shows the form of 

 the underlying strut. 



heel. There was certainly no knob on either marginal 7 or marginal 2 in the specimens 

 where those ossicles are visible. 



§ 214. Correlated with the obliquity of the front part of the leg, the rectal passage 

 between marginals 11 and 12 (or 1) is narrowed almost to a point, and those elements 

 had, apparently, no flat downward extensions (see especially G5 and G33). 



§ 215. The tag and tongue processes are not shown in any of the specimens where one 

 might have expected to see them, and I incline to think that, like the toe-spine and 

 the knobs on marginals 2 and 7, they were not so well developed as in C. Elizae, for 

 the following reason : In all the specimens the frame seems to be bent in such a way 

 that, if it were resting on the sea-floor, it would touch it by the end of the toe, by the 

 knob on marginal 6, by the frame at the back of the heel and leg, and by the top end 

 of the leg, while the middle region would have been raised in an arch. Hence the 

 trivial name, curvata. 



