Ob MESSRS. HANCOCK AND ATTHEY ON 



stretches upwards and forwards. The teeth vary somewhat in 

 number ; they are usually about twenty-five, which are arranged 

 along the alveolar margin in regular order. This regularity, 

 however, is frequently disturbed by the approximation of two or 

 more ; sometimes three or four are placed close together. 



The premaxillaries are long narrow bones, about as long as 

 the maxillaries, being usually -roths of an inch in length, and 

 nearly in^-ths of an inch broad. The alveolar margin is almost 

 straight ; the opposite margin gently slopes backwards in a some- 

 what sinuous course, so that the bone is pretty regularly wedge- 

 shaped, the posterior extremity being pointed. There are about 

 the same number of teeth as in the maxilla, with the addition of 

 a large conical laniary tooth in front, immediately before which 

 is a small tooth or two. 



The mandibular bone we have never seen quite perfect : one of 

 the most complete in the series measures l-rb-th inches in length, 

 and about -roths of an inch wide near the front ; the upper and 

 lower margins are nearly parallel ; it is rounded in front, and 

 appears to taper a little at the posterior extremity ; the ante- 

 rior extremity is slightly bent upwards. There are from fifteen 

 to twenty teeth in our fragments ; the number must be much 

 greater in the entire ramus. There is likewise a large laniary 

 tooth in front, and three or four others placed along the ramus, 

 in a line within the small teeth ; in front of the anterior laniary 

 there is a small tooth or two like those in the praemaxilla. These, 

 however, are not always to be seen ; and the posterior laniary 

 teeth are very rarely present, or are perhaps frequently buried 

 in the matrix. They are placed at some little distance from each 

 other ; and the small external teeth, like those of the upper jaw, 

 frequently exhibit considerable u-regularity, though on the whole 

 they are placed apart at pretty regular intervals. The above 

 description of the jaws applies to those of the usual size ; but 

 we have a mandibular bone which, if complete, would be up- 

 wards of three inches long, and a maxillary or two of corres- 

 ponding dimensions. 



The laniary teeth are grooved at the base, and here the periphe- 

 ral dentine is a little infolded or plicated ; and in fine specimens 



