MKKHIAM: TRIASSir IOITTTTYORAT T RTA. 



135 



present in specimen number 9086. The determinal ion of those bones was f<> 

 some extent tentative in the study of the first specimen, but seems now fully 

 justified by what is known of the pelvis of other Triassic ichthyosaiinans in 

 which the position of the elements is definitely determined. The pelvic hones 

 are in general much like those of ,s7m.sY^.sw//v(x. The ilium is distinguished 

 from that of all the other Triassic genera by the presence of a tubercle near 

 the outer side of the proximal end. This tuberosity is indicated on both of the 

 known specimens, and has not thus far been seen in any other form. The 

 ischium is somewhat broader than in Sinistdsnnrtin. In the pubis the proximal 

 end is not as wide as in S. ixn-ificiis, while the distal hook is not as strongly 

 curved as in that form. 



The posterior limit (fig. 147) shows much the same stage of development as 

 the posterior one in S. OHM out i (no. 

 9608; see figs. 100-101, p. 66). The fe- 

 mur is more distinctly abbreviated than 

 in Cymbospondylw, and is somewhat 

 broader than in S. osmonti (no. 9608). 

 The tibia and fibula both show a median 

 constriction. The tibia is much larger 

 than the fibula and has nearly the same 

 width at the two ends. The fibula is 

 expanded at the distal end, but as in 

 Cymbospondylus the proximal end is 

 barely wider than the middle of the 

 shaft. Several discoidal limb elements 

 are present with the hind limb of the 

 type specimen, but it is uncertain 

 whether they represent mesopodial or 

 phalangeal elements. 



A considerable part of the skull is 

 present with specimen 10998, and a por- 

 tion of the cranium with specimen 9082, but as yet it has not been possible 

 satisfactorily to free the delicate bones from the hard matrix. 



Of specimen 9082 there are given below the measurements of three an- 

 terior dorsal vertebrae, which correspond in their position to about the 15th, 

 16th, and 17th in the vertebral column ; a fourth is near the position of the 25th 

 vertebra. 



MEASUREMENTS, SPECIMEN 9082. 



15th vertebra, anteroposterior diameter of centrum 21.3 mm. 



15th vertebra, height of centrum 30 



15th vertebra, height of upper arch 41 



Fig. 147. Delphinosaurus per'rini Merriam. 

 Posterior limb, X %. 



