366 



BRACHIOPODA OF THE 



possessed all the interior characters of Hall's genus Dinobolus, of which genus Prof. 



King and myself had given an elaborately illustrated description in vol. xxx of the 



'Quarterly Journal of the Geological Society' (1874). In August, 1880, I inserted an 



article upon the subject in the ' Geological Magazine.' 



Bivalve specimens seem very scarce at Budleigh-Salterton, but in Prance they appear 



to be abundant, and so we had better complete our description of the species from the 



more complete Prench material. 



Shell very variable in shape, marginally subquadrate, with anterior rounded angles 



and slightly indented front. Sometimes the shell is triangular, and widest anteriorly. 



Dorsal valve very convex and inflated, especially at the umbo, flattened at, and close to, the 



cardinal line and extremities. Ventral valve not so deep as the opposite one, with a 



longitudinal mesial depression on the anterior half of the valve; beak small and very 



little produced. Surface of valves smooth, and 

 marked with numerous concentric lines or project- 

 ing ridges. On the interior surface of the ventral 

 valve there exists a broad slightly raised platform 

 (fig. 1), on which are situated the lateral and 

 anterior muscular scars (o and n) as well as the 

 crescent (r). On the interior surface of dorsal valve 

 (fig. 2) the crescent (r) is well defined, as well as 

 the V-shaped lateral and median scars (o and m). 

 Dimensions very variable. Two specimens mea- 

 sured respectively — 



Dinobolus Brimonti, Rouault, sp. 



1. Interior of ventral valve: o, n, anterior me- 

 dian muscular scars ; r, crescent. 



2. Interior of dorsal valve : r, crescent ; o, m, 

 lateral and median muscular impressions. 



Length 19, width 17, depth 13 lines. 

 jj 15j »j 16, ,, 8 ,, 

 Dinobolus Brimonti does not appear to be a very abundant fossil in the Budleigh- 

 Salterton pebbles. Abroad, in addition to Guichen and Bain, we may mention Pontrean, 

 in Brittany, and in his memoir M. de Tromelin adds Chateaubriant. At the Butte des 

 Kidais, Ruffigne, Sion, the shell attains to larger dimensions than in any other of the 

 localities referred to ; two examples measured respectively — length 20, width 24 lines ; 

 length 21, width 15, depth 16 lines. M. Moriere found it also in the Gres de Bagnoles 

 (Orne). 1 M. C. Barrois informs me that this fossil occurs also in the Meney-Hom 

 Mountains. 



1 I may likewise observe that subsequent to the publication of the memoir by King and myself on the 

 Trimerellids, Prof. Fred. Schmidt discovered in a light yellowish limestone at Laisholm, in Russia (his 

 Schicht 5) a number of internal casts of a small species of Trimerella, and at Werden, in the same country 

 (in his Schicht 6), a species of Monomerella. So that examples of this important family of Brachiopoda 

 are now known from Sweden, Russia, France, England, Canada, and the United States, and will no doubt 

 with time be found in other places. Dinobolus Brimonti is the most ancient representative of the genus 

 with which we are at present acquainted. 



