1 1 sTLDiiNin.i:. 415 



convex backward. The pectorals occupv 50 mm. of the midline. I he sulci bounding them 

 behind are rather strong^ convex forward. The abdominals are large, pining along the 

 midline for a distance of I 15 mm. The temorals and the anals have about the same fore-and- 

 aft extent, 40 mm. 



The fragment of the carapace of the tvpe individual has not been treed from the closely 

 adhering matrix. 



In the collection made by Mr. Isaac there is a specimen ot a rather small individual, No. 

 [326, which furnishes a considerable portion of the carapace (plate 19, fig. 5), as well as the 



characteristic parts of the plastron. All the neurals are repre- 

 sented in whole or part, and in the same way are represented 

 most of the costal plates. The dimensions ot the neurals are 

 shown in the table. 



The first neural is broader behind than in front, and there is 

 on its anterior end a prominent boss. The second and fourth 

 neurals are octagonal. The third is represented by only a part; 

 but it was doubtless quadrangular, with the lateral borders con- 

 vex. The fifth is hexagonal and short. The sixth is hexagonal, 

 with the antero-lateral sides longer than the postero-lateral; while 

 the seventh is hexagonal, with the antero-lateral sides shortest. 

 The eighth is hexagonal and elongated fore and aft. 

 The costals of this species are strongly modified as regards their width. The third articu- 

 lated with the second, third, and fourth neurals. It has a proximal width of about 30 mm., 

 while its distal end is only 16 mm. wide. The fourth is very narrow at its proximal end, but 

 it rapidly increases in width, being distally 43 mm. The fifth costal articulates with the 

 fourth, fifth, and sixth neurals; is 28 mm. wide proximally and 15 mm. distally. The sixth is 

 17 mm. wide proximally and considerably wider at the distal end. The costals are markt on 

 their distal halves with grooves and ridges, produced by the growth of the scutes. 



The first vertebral scute had a width of 50 mm. at the anterior end and about 45 mm. at 

 the hinder end. The third has been 66 mm. wide at the middle of its length; the fourth, 53 mm. 

 Another specimen, brought from the same region by the same collector, had a carapace 

 about 330 mm. long. But little of the plastron is present. The carapace is crusht and various 

 parts are wanting. The number of this individual is 2894. This carapace is peculiar in having 

 the fourth neural hexagonal, instead of octagonal. The sixth costals expand distally, being 

 there 40 mm. and 22 mm. proximally. The seventh costals are narrow, 21 mm. proximally, 

 14 mm. distally. 'I he ninth peripheral had a thickness of 11 mm. The anterior vertebral 

 scute had a width of 78 mm., while the fifth was 122 mm. wide. 



All the vertebrae of the neck of the tvpe specimen (fig. 540) are present except the first 

 and second. On comparison with the corresponding vertebrae of a specimen of T. radiata 

 whose plastron is two-thirds as long, it is found that the neck of T. vagawas relatively shorter 

 than that of the T . radiata, but the centra are in size proportionally broader. There are 

 some differences in the zygapophyses worthy of note. In T. radiata, the prezygapophyses of 

 the sixth cervical rise to a height of 10 mm. above the lower border of the centrum, and the 

 zygapophyses measure only 4 mm. each across the articular surface. In T. vaga these prezyg- 

 apophyses rise to a height of 20 mm. and are 11 mm. across. The postzygapophyses of 

 the eighth cervical of T. radiata have a length of 7 mm.; those of T. vaga a length of 22 mm., 

 a difference out of all proportion to the sizes of the two animals. The cervicals of the latter 

 are in fact as large as those of a Chelydra of the same size. 



Herewith are furnisht figures of the scapula and the coracoid of the left side (figs. 541, 

 542). These parts do not differ in any important way from the same bones of Gopherus 

 polyphemus, altho they are proportionally stouter. The coracoid is 64 mm. long and 61 mm. 

 broad at the inner end. The neck of the bone is 14 mm. wide. 



The vertebral end of the scapula is missing, so that the length can not be stated. Above 

 the glenoid cavity the bone is much comprest. The comprest procoracoid process (fig. 541) 

 has a length of 60 mm., measured from the center of the glenoid cavity. 



The humerus ! fig. 543) resembles closely that of Gopherus polyphemus, altho stouter in 

 build, resembling 111 this respect that ot T. radiata of Madagascar. As a portion of each of 



