252 Messrs. Davidson & Morris on some species of Brachiopoda. 



space for the animal ; beak small, not much recurved, entire, and 

 not perforated at the extremity ; area smaller than the greatest 

 width of the shell ; deltidium very large. 



The interior of the ventral valve presents some characters re- 

 sembling Chonetes, but it has no tubes on the cardinal area, which 

 are considered by M. de Verneuil and others as characteristic of 

 that genus. Round the internal edge of the ventral valve is a 

 row of tubercles, which diminish in size towards the front of the 

 shell, and the centre has a ridge also tuberculated, the remaining 

 space, interiorly, being covered by a fine irregular punctuation, 

 which in this respect has some analogy to Chonetes ; but in that 

 genus the median tooth is terminated by a point ; in our shell 

 this tooth presents externally three or four grooves, as in the 

 genus Leptcena : this and other characters have induced us to 

 place the species under Leptcena, although it possesses so many 

 characters common to both genera, that it may be considered as 

 forming a connecting link between them. 



This species is readily distinguished from Leptcena liasiana by 

 its more elegant form, the ventral valve of L. Bouchardii is more 

 regularly concave, and the dorsal valve more convex ; in this spe- 

 cies also the beak of the dorsal valve is entire, in L. liasiana it is 

 always truncated and perforated, and the front is indented and 

 not so regularly rounded as in L. Bouchardii. 



Rather more than a line in width and one and a half in length. 



This species never attained a very large size, as the internal cha- 

 racters presented by the ventral valve appear to be those belong- 

 ing to a full-grown shell. 



Found by Mr. Moore, associated with L. Moorei, in the 

 Leptsena bed previously described under that species. 



It is dedicated to M. Bouchard of Boulogne, who has kindly 

 examined the species and assisted in defining the characters which 

 distinguish it from L. liasiana, to which it bears the greatest 

 resemblance. 



Leptcena Pearcei, Davidson. PI. XVIII. fig. 4 a, b. 



Of this small species the dorsal valve is only known, which 

 shows that it differed materially from L. Moorei by this valve 

 being much more convex, and the striae which ornament its sur- 

 face having two or three smaller ones between each larger one, as 

 seen in fig. 4 b, while in L. Moorei the costse appear of the 

 same size ; the shape of the shell is also more rounded and larger 

 than L. Moorei. Rather more than 2 lines long and 3 broad. 



This species occurs in a clay stratum above the Leptsena bed 

 containing L. Moorei, and not associated with it. 



Also discovered by Mr. Moore, and dedicated at his request to 

 his late Mend Mr. C. Pearce of Bath. 



