410 



DR F. A. BATHER. 



^ 216. In this connection it may be noteworthy that the stem in all cases appears 

 to be attached rather nearer to the reverse side of the theca than in C. Elizae. 



§217. The plates of the integument are more prominent than in C. Elizae, ^vA 

 in many places appear imbricate. This may be only the expression of a chance con- 

 traction, but, even so, it points to some slight difference of structure. 



§ 218. The Subvective System occupies a curved tract, having an outline not 

 greatly differing from that of C. Elizae, and bearing the same general relations to the 

 toe and stem regions of the thecal frame (PL IV. figs. 39, 44). In these respects the 

 only notable diff"erences are a slightly greater width at the toe end, and an extension 

 further over the stem, such as might have been facilitated by the diff"erent slope of 

 the strut (§212). 



Fig. 26. Fig. 27. Fig. 28. 



Text-figs. 26-28. — Cothurnoajstis curvata. All figures enlarged 12 diameters. . 



Fig. 26. — External view of two grooves of the subvective system, based on G24 



(cf. PI. IV. fig. 44). 

 Fig. 27. — Internal view of two grooves of the same specimen (cf. PI. IV. fig. 43). 

 Fig. 28.— Solid section of the four dimeres of the proximal region of the stem, based 



onGl (cf. PI. IV. fig. 45). 



But, since the frame itself has grown outwards at the ball of the foot, the subvective 

 tract is not parallel to the frame as in C. Elizae, but between it and the frame there 

 lies an area of plated integument with its greatest width equal to that of the subvective 

 tract, and tapering towards the toe and the stem. 



Though in shape, length, and width, the subvective tract of C. curvata diff"ers almost 

 inappreciably from that of C. Elizae, it presents a totally diff'erent appearance, due to 

 the narrowness and compression of the elliptical subvective areas. The ratio of width 

 to length in these is about 1:10. In G24, for instance, the greatest length of the 

 ellipses is 3 mm., and there are 36 ellipses observable in a tract of 9 mm. long. In 

 Gr2 about 42 ellipses are observed in a tract 13 "5 mm. long. 



Seen from the outside, each ellipse appears as a narrow, slightly rounded ridge 

 (text-fig. 26). In 0-24 (PI. IV. fig. 44) the ridges near the middle of the subvective 

 tract have a width of "26 mm. or less, and a length of 3 '05 mm. or less ; but, owing to 

 the slight curvature of the ridges, the actual length is a trifle more, so that the ratio 

 in these is 1:12, The ridges are close together, so that the space between two ridges 

 rarely exceeds "07 mm. One gets the impression, therefore, of a number of parallel 



