TOXOCHELYIDJE. 



173 



plate Ixxxiii, belong to No. 1270. There appears to be no reason for doubting that these bones 



all belong to the same species. 



The principal differences between the present species and Cope's T. serrifer must be sought 



in the form of the lower jaws and of the peripheral bones. Unfortunately we can not determine 



the form of the anterior nares of T. serrifer. 

 The lower jaw of T. serrifer shows no indica- 

 tions of a beak, while that of T. stenopora 

 (figs. 214-216) is plainly beakt. Case recog- 

 nized this difference. The table herewith 

 presents the dimensions of the two jaws. 



It is seen from these measurements that, 

 although the lower jaw of T. stenopora, as 

 represented by the masticatory surface, is 



is nevertheless deeper, the inner face of equal 

 depth, and the symphyseal line of the masticatory surface longer. The width of the inner 

 face of T. stenopora may be somewhat greater than the figures indicate, since there is evi- 

 dence of some downward crushing. The symphyseal line above slopes downward and back- 

 ward in T. stenopora; in T. serrifer, it is nearly horizontal. 



The peripherals of T. serrifer are much broader and flatter in proportion to their length 

 than in T. stenopora. Thus, in comparing what appear to be the eighth peripherals, we find 

 that of T. serrifer measuring 49 mm. in length and 32 mm. in width, while that of T. steno- 

 pora is 23 mm. long and 10 mm. wide. 



The bones bearing the number 2060 of Kansas University museum are made the type 

 of the present species, and in case it should be found that the skull and the other bones of 

 2060 are not all of the same species, the former is to be regarded as the type. 



As will be seen from the figures (figs. 217, 218), the skull has been damaged, especially the 

 hinder portion. Nearly the whole of the roof of the temporal region is missing. The quadrates 

 and the supraoccipital are present, but detacht from the rest of the skull. Dr. Case's figures 

 represent the skull as larger by one-half than the originals; but this has probably been due to 

 the failure of the engraver to reduce the original drawings. 



The skull was evidently short and broad. The distance between the hinder ends of the 

 maxillae equaled the distance from the snout to the middle of the basisphenoid; whereas in 

 T. latiremis the distance between the extremities of the maxillae extends only to the narrowest 

 portion of the pterygoids. The length of the skull to the hinder border of the basisphenoid is 

 46 mm.; to the occipital condyle was probably about 10 mm. more; while the length to the 

 hinder end of the supraoccipital bone was about 82 mm. The palate, where narrowest, is 

 10 mm. wide; the interorbital space, 13 mm. The alveolar surface of the upper jaw, including 

 the rough ridge on the palatine, is relatively broader than in T. latiremis, being contained in 

 the length of the cutting-edge 3 times. In T. latiremis it is contained 4 times. This increase 

 in the width of the surface appears to be at the expense of the fossa for the choanae, which is 

 but little wider than the surface referred to; whereas in T. latiremis the fossa is much wider. 

 In the wideness of the alveolar surface and the narrowness of the fossa the present species 

 resembles T. procax. 



There were without doubt posterior palatine foramina, as in the other species of the genus. 



That which distinguishes this species from all others of the genus, so far as known, is the 

 narrowness of the anterior nares. This slit-like opening is evidently natural, or due only very 

 slightly to any compression during fossilization. The skull is flattened somewhat by pressure, 

 from which condition we may conclude that the narial opening originally had possibly a more 

 perpendicular position than at present. 



A portion of one parietal bone is among the remains of the skull. It presents a part of 

 the roof of the temporal region. The supraoccipital (fig. 219) has a length of 35 mm. and a 

 maximum height of 16 mm., being thus relatively long and high. 



This skull is accompanied by the pygal and nearly all of the peripherals of one side. Some 

 of these have been figured by Dr. Case (op. cit., plate Ixxxiii, fig. i). The pygal has a sharp 

 posterior border and a rounded anterior border. From the latter there springs a process which 



