1854.] OWEN PURBECK FOSSILS. 423 



crown of these teeth is broad, laterally compressed, with an almost 

 semicircular contour, and slightly pointed where unworn, as at a, fig. 6 ; 



Fig. 6. — Pai^t of the right side of the upper jaw, with teeth, of the 

 Macellodus Brodiei, Owen. (Nat. size, and magnified.) 



a, b. Two of the teeth magnified. 



but some of them exhibit the summit either worn away or broken ofi^, 

 as at 6 : the enamel is marked by very fine longitudinal ridges, which 

 give a subcrenate character to the unworn margins of the crown. 

 The third tooth in the present specimen exhibits the minute germ of 

 a successional tooth entering the cavity on the inner side of its base. 

 The eighth tooth is represented by the apical half of the crown, which 

 has not arisen to the level of the outer alveolar groove : the tooth 

 which this germ was in course of succeeding has been shed or broken 

 away. The third and sixth teeth are less advanced than the second, 

 fourth, and fifth teeth. 



The inner part of the alveolar groove, from the second to the 

 seventh tooth inclusive, terminates internally in a free smooth convex 

 surface, which has formed the outer boundary of a wide and extended 

 palatal vacuity, as in modern Lizards. Beyond this the upper jaw 

 expands to join the palatine bone. This structure, with the unequal 

 development, and the evidence of the succession, of the teeth, toge- 

 ther with their mode of implantation, gives unequivocal proof of the 

 saurian nature of the fossil in question. From the resemblance of 

 the teeth of this small Lizard to the blade of a spade, I propose to 

 call the genus which it represents Macellodus (jua/ceXXa, a spade, 

 olovs, a tooth), and the species, in honour of its discoverer, Bi'odiei. 



The specimen was obtained from a part of the Purbecks, marked 

 K. 93. in Mr. Austen's ' Guide,' and called the " dirt-bed, containing 

 shells*," high up the cliff, at Durdlestone Baj^, Isle of Purbeck. 



To the same species belong some at least of the organic remains 

 in the specimen marked K. 7. in Mr. Brodie's collection. 



This is a block from the Purbeck formation of a laminated marly 

 character, from the lower part of the so-called " dirt-bed, containing 



* The specimens of this deposit sent with the bones contain Physa Bristovii ?, 

 Valvata, Limnmis, Cypris, and vegetable remains. 



vol. X. — PART I. 2 G 



