MKHIUA.M Till". TIIAI.ATTnsAlMMA / 



The iiivcrt('l)nitc faunas have Ix'tMi extensively studied Ky Professor 

 Smith', and are referred 1)V him to the I'pper Triassic on the eviih^iee of general 

 striking simihiritv of thi' fauna to that of the Alpine Triassie of Europe, even in 

 some cases to the point of identity of speeies. Also in the ease of the lehthyo- 

 sauria, almost uncjuestionable evidence of late Triassic age is Liixcii in the stage 

 of evolution or specialization of various parts of the skeleton. In general this 

 is near the stage i-eacheil hy the hditliyosauria of the latei- Triassic of Italy. 

 This is particulai'lv noticealile in the structure of the lindis. girdles and 

 vertel)i-al arches. 



The preseiKH' of innumi-rahle cephalopods with hracdiiopods and corals, 

 in a limestone containing for the most jiart hut little argillaceous material, 

 leaves no room for doul)t that the deposit was formed in a fairly (dear sea, into 

 whicli there was but little drainage at this point. The reptilian forms whicdi we 

 tind in these strata evidently Ixdonged to the typical marine fauna of tlu- late 

 Triassic. 



MATEHIAbS AVAILAUI.E. 



The specimen whiidi has furnished the most satisfactory information in 

 this investigation is the tvj)e of Tliahitfosdurus ukxcnidrae (No. ilOS;")). Excepting 

 the anterior part of the skull and portions of the limbs and girdles, the skeleton 

 had long been exposed and was larg(dy weathered away. The remaining part's 

 include the anterioi' two thirds of the skull with a small jiart of one temporal 

 region. Of the girdles and lindis there are present the scapula, coracoid, 

 humerus, ulna, three l)ones wiii(di represent the lower part of the pelvis and 

 possibly the fenuir, and some scattered ossicles which may be either carpals or 

 phalanges. ()f the vertebral column there are pai'ts of about thirty vi-rtebrae 

 extending in an interru})te<l series fi'om the hea<i to the anterior caudal region. 

 There are also nunu'rous scattered true ribs and abdominal ribs. 



.\noth(M' specimen (Xo. '.)()S4 ), certainly of the same species, shows a por- 

 tion of the skull with good mandible and (juadrate, also both humeri, a radius 

 and several well preserved doi'sal vei'tebrae. 



Two other smaller skulls having the same size and form ai'e also referre<l 

 to TJialaitosaarm but probably do not Ixdong to the type species. ( )ne of them 

 (7^. sliastensis. No. 1)120) shows the innei- side of the j)osterior half of a skidl in 

 good state of preservation. With it are several good vertebrae, limb bones, ribs, 

 abdominal ribs and teeth. In the second specimen the ]iosterior three 

 fourths of the skull are present, fairly preserveil but very difficult of preparation. 



1 Lor. fit. 



