444 PKOCEEDINGS OP THE GEOLOGICAL SOCIETY. 



nasal aperture *, which, moreover, in Mosasaurus looks directly up- 

 wards instead of upwards and forwards, in the total obliteration of 

 the maxillo-praemaxillary suture, which, in Mosasaurus, remains as 

 a well-defined groove, and, lastly, in the absence from its cylindrical 

 teeth of the opposite denticulated ridges, the total range of variation 

 in the teeth of Mosasaurus including at most teeth exhibiting the 

 suppression of one of these (the anterior), and that on the pterygoid 

 teeth f. 



I propose for this reptile the name of Acrodontosaurus Gardneri— 

 the first obviously in allusion to the mode of attachment of its teeth, 

 the second out of compliment to my indefatigable friend. 



The strata of the locality whence this fossil came were so fully and 

 ably described by my friend Mr. Etheridge in fixing the position of 

 AcantJiopJiolis horridus, Huxley, that it will only be necessary to say 

 that it was obtained by Mr. Griffiths from the Lower Chalk of Lyddon's 

 Spout, near Polkestone, about 10 feet above the Chalk marl. 



It will, I think, be better to leave the discussion of the affinities 

 of this reptile till further discoveries furnish a better character for 

 our guidance than the mode of implantation of the teeth, 



EXPLANATION OF PLATE XIX. 



Fig. 1. Side view of upper jaw of Acrodontosaurus Oardneri, nat. size : h, pro- 

 cess of prsemaxilla ; c, osseous base of shed tooth ; /, terminal facet ; 

 g, groove. 



2. Front view of the same : S & / as in fig. 1. 



3. Yiew of fractured hinder end ; «, inner projection. 



13. EODENTIA of the SOMEESET CavES. 



By "W. Atsheoed Saneoed, Esq., F.G.S. 



(The publication of this paper is deferred.) 



[Abstract.] 



The author has examined the Rodents from the caves of Somer- 

 setshire contained in the Taunton Museum, and found that many 

 of them cannot be referred to species hitherto regarded as belong- 

 ing to the fauna contemporary with the Mammoth in Britain. He 

 enumerates species oiArvicola (including A. glareola, Schreb., and A. 

 ratticej>s, 'Bias. =Lem'mus medius, Nilsson, and a species which may 

 be new, and for which he proposed the provisional name of A. 

 Oulielmi), Lemmus (L. norvegicus, Desm.), Lagomys {L. spelceus, 

 Owen), Lepus {L. diluvianus, Pict., L. timidus, Linn., L. hihernicus, 

 Bell, and L. cuniculus, Linn.), Spermophilus (S. eryihrogonoides, 

 Falc. : the citation of S. citillus by the author and Mr. Boyd Daw- 

 kins is founded on a mistake), and Cricetus (C. songarus, Pall.). 



* Goldfuss in Nova Acta Acad. Nat. Cur. vol. xxi. p. 1, tab. vi.-viii. 

 t Teste Dr. Leidy. 



