120 OLD RED SANDSTONE FISHES. 



Bothriolepis obesa, Traquair. Plates XXVII and XXVIII. 



1888. Bothriolepis obesa, Traqua i r. Geol. Mag. (3), vol. v, p. 510. 



1891. A. S. Woodward. Cat. Foss. Fishes Brit. Mus., 



pt. ii, p. '228. 

 1893. Traquair. Proc. Roy. Phys. Soc. Edin., vol. xi, 



p. 285. 



Specific Characters. — Anterior median dorsal plate carinated; the other [dales 

 indicate a peculiarly short, thick-set form of carapace; tuberculatum similar to that 

 of ]J. major. 



Description.— AM the figures illustrating this species on PI. XXVII and XXVIII 

 are three quarters natural size. 



The specimens used as types by me in my original brief description ('Geol. 

 Mag.,' 1888) are from the neighbourhood of Jedburgh and must therefore be 

 noticed first. 



In PI. XXVIII, Fig. 1, is shown a specimen of the right anterior ventro-lateral 

 plate, cut off behind by the edge of the stone, but showing the regularly convex 

 outline of the anterior margin in its entirety. The position of the large articular 

 fossa for the pectoral appendage is seen as well as the remains of the brachial, or 

 " helmet " process itself. More than one half of the bony substance of the plate 

 has flaked off, showing the smooth internal cast below ; what remains is, however, 

 of considerable thickness, and is ornamented by a confluent tuberculatum similar 

 to that which occurs on most plates of B. major. 



In Fig. 2 we have a specimen of the left anterior ventro-lateral plate, unfortu- 

 nately deficient at the anterior and external part in front of the articular fossa; 

 otherwise the contour of the plate is complete. The first thing which strikes the 

 eye is the large size of the articular fossa and its relatively posterior position on 

 the outer side of the plate ; and the next is that the posterior margin of the ventral 

 or horizontal portion of the plate passes obliquely across in a slightly convex line. 

 Along the inner margin we see very distinctly the narrow area, overlapped by 

 the corresponding plate of the other side. 



Fig. 3 shows the horizontal part of the left 'posterior ventro-lateral plate, 

 deficient, however, posteriorly, as the hinder extremity is cut off by the edge of 

 the stone. Here the anterior margin is seen to pass straight across, cutting the 

 inner one at a right angle, which seems to show no truncation for a median 

 ventral. Was the last named plate absent in this case? I think not; my 

 explanation of the appearance being that the anterior margin of the plate is 

 deficient. 



