OARADOCIAN CYSTIDEA FROM GIRVAN. 



399 



process from a marginal at the hollow of the sole. Thus the enclosed area is divided 

 into a toe-half and a heel-and-leg half; and each space is filled by a finely-plated 

 Integument, attached to the edges of the channelled marginals on the side next 

 the observer. 



§ 164. At the toe end, the boot is upturned and prolonged into a spine, like a 

 pointed mediaeval shoe. At the opening of the leg are, in the genotype, two flattened 

 processes : one comparable to the tag by which a boot is pulled on, the other like a 

 large projecting boot- tongue. 



§ 165. Some of the marginals bear large Knobs or spines, projecting at right angles 



tongue 



toe-spine 



heel 



ball of foot 



tag 



heel 



Fig. 14. — Reverse. 



Fig. 15. — Obverse. 



Text-figs. 14, 15. — Cothurnocystis Elizae. 



Reconstructions of the two faces, based on the various specimens mentioned in the text. Probably no individual quite 

 reached the size of these figures, though a few fragments come very near it. The numbers 1-11 refer to the marginals beside 

 which they are placed. The proximal and median regions of the stem are drawn, with a few columnals of the distal region. 



KiG. 14. — The reverse face, showing the strut, the knobs on 2, 3, 6, and 7, and the flattened plates of the integument. 

 Fig. 15. The obverse face, showing the vent, just below the number 11, the subvective system by marginals 5 to 7, and the 

 irregular rounded plates of the integument. 



to the plane of thecal extension. These, one supposes, served as legs to support the 

 framework above the level of the loose sand and to hinder it from being dragged by 

 currents. They are placed, in both species, one at each lower {i.e. adcolumnal) corner 

 of the theca, and, in C Elizae only, one half-way up each side, so that the centre 

 of gravity of the theca would tend to lie above them. The balance, however, is 

 restored by — 



§ 166. The Stem, of which the main characters are given above (§ 160). It is 

 attached to the frame, in the hollow of the sole, on the side of the strut next the ball of 

 the foot. Its tapering to a fine point proves that it was used neither for support nor 

 for attachment. 



§ 167. Viewed from the Upper or Obverse face (text-fig. 15), the frame differs in 

 TRANS. ROY. SOC. EDIN., VOL. XLIX. PART II. (NO. 6). 53 



