1854.] OWEN PURBF.CK FOSSILS. 425 



hibits long diapophyses, as in the lumbar and anterior caudal verte- 

 brae of most modern Lizards, a moderately long spine, and a circular 

 neural canal : the exposed surface of the arch is fractured, and the 

 zygapophyses have been removed. There is no trace of the verte- 

 bral body, which has most probably been detached from the sutural 

 connection with the arch, before this became imbedded in the present 

 matrix. 



In modern Laeertilia the neural arch anchyloses with the centrum 

 at an early period, but in the Crocodilia it retains its sutural union. 

 On the supposition of the neural arch being separated from a sutural 

 union and not broken away, that arch would accord with the croco- 

 dilian characters afforded by the subquadrate scutes ; the size of the 

 two parts also supports their reference to the same animal. The 

 presence in the same block of the Lacertian jaws and teeth leads to 

 a suspicion that they belong to the same reptile ; but similar croco- 

 dilian scutes are associated, in another block of Purbeck clay, with 

 jaws and teeth of an animal to which they could not have belonged. 



The length of the portion of the dentary bone containing the 

 thirteen teeth is 1 7 millimetres, or 9 lines. 



The breadth of the neural arch across the diapophyses, and in- 

 cluding them, is 20 millimetres, or 10 lines ; the long diameter of 

 one of the scutes is 1 7 millimetres, or 9 lines ; its breadth is 6 lines, 

 or 13 millimetres. 



Fig. 7 « is a magnified view of one of the anterior teeth, and fig. 7 b 

 of one of the hinder teeth in the dentary bone, fig. 7. 



As the anterior teeth in this specimen present nearly the same 

 degree of resemblance to those figured in my ' Odontography*,' 

 that have been referred to the Hylceosaurus, as the teeth of the 

 Nuthetes do to those of the Megalosaurus, it became equally neces- 

 sary to consider the question of the relationship of the Macellodus 

 to the Hylceosaurus, as being possibly the young of the latter Wealden 

 reptile. 



The teeth of the Macellodus that most resemble those of the 

 Hylceosaurus do not present so long and cylindrical a base, so 

 angular an expansion of the crovpn, or the mode of abrasion of the 

 crown by two sloping facets meeting at an angle of 80°, which is 

 peculiar to the presumed Hylseosaurian teeth : moreover, the cor- 

 respondingly enlarged representations of the spade-shaped teeth of 

 the Macellodus have not yet been met vdth in the Wealden strata 

 that have yielded the teeth and other remains of the Hylceosaurus. 



The large Saurian teeth that come nearest in shape to the typical 

 and most numerous teeth of the Macellodus are those of the Cardio- 

 don of the Forest Marble of Wiltshire (Odontography, pi. 75 A. 

 fig. 7 «), and of the Palceosaurus platyodon of the Magnesian 

 conglomerate (op. cit. pi. 62 A. fig. 7) : but the differences which 

 will be seen on comparing the enlarged figures of the teeth of 

 Macellodus, figs. 7 & 9, with the above-cited figures, are not recon- 

 cileable with the supposition that they might be due only to a differ- 

 ence of age of individuals of the same species. 

 * Vol. i. pi. 62 A. fig. 8 a, b. 



2 G 2 



