18 PEOCEEDINGS OF THE ACADEMY OP 



Stands above the parapophysis of the sixth. They are nearly united with the 

 parapophysis on the third cervical, and are no doubt fully so in mature age. 

 The fourth cervical is lost, but it is scarcely jjrobable that it presented a com- 

 plete ring for the transmissal of the vertebral artery, etc. There are no rings 

 attached to the vertebra; from the fifth inclusive. The centra are all trans- 

 versely oval. 



Inches. 



Height centrum and arch of axis r2-25 



" centrum 7- 1 



Transverse extent of axis 25* 



" " centrum of do 11- 5 



" " neural canal 5-75 



" " of third cervical 23' 



" " centrum do !!• 



Length parapophysis sixth cervical 5- 



Vertical diameter centrum (? 5th) dorsal 7* 



Length centrum do 6* 



Vertical diameter centrum second caudal, with perforate diapophyses... 10-5 



Length centrum do 10'5 



Height spine and arch middle lumbosacral 14-5 



" from floor canal to top anterior zygapophysis do 6- 



There is no neural spine on the second, third and fourth cervicals, and it is 

 rudimental and small on each of the remainder. Those of the dorsals and- 

 lumbars are not particularly elevated. 



The humerus is very short and thick, and the hand remarkably small. 

 The scapula, as in other Sibbaldii, has considerable antero-posterior extent, 

 and well developed acromion and coracoid. The disk is divided into three 

 areas on the inside, by two slight ridges. 



Dimensions. 



Inches. 



Antero-posterior width , 33- 



Vertical " 21- 



Length acromion 7*5 



" coracoid 4-5 



Diameter of glenoid cavity 8- 



The muzzle is elongate, and with a narrow acumination. The supraorbital 

 plates of the frontal are 



Each nasal is as wide as long medially; anteriorly concave above, the line 

 of junction of the two in one plane, forming a median ridge, which is prolonged 

 into a prominent median point. The otic bulla; are slightly compressed and 

 carinate below, and their surface is not markedly rugose. The malars are in 

 shape something like first ribs ; that is, with an enlarged head, with promi- 

 nences imitating capitulum and tubercle, a short narrowed shaft, and expanded 

 distal extremity. The distal third is occupied by an ovate ? articular surface, 

 thinning out the margin on one side. The shaft is thin and concave, both lon- 

 gitudinally and transversely, on one side. 



The inner margin of the palatine bones is regularly continuous with the 

 short pteiygoids, which are very short, and do not approach near tiie otic bul- 

 la; ; Rudolphi represents the latter as prolonged to beyond the extremitj- of the 

 bulla. The posterior plate of the vomer in S. tectirostris extends much 

 further posteriorly than Rudolphi represents for the S. laticeps, and though 

 there is no doubt some variation in this respect in the same species, the differ- 

 ence is here very considerable. In S. 1 a t i c e p s it extends to a little behind 

 the anterior margiu of the bulla ; in S. t e c t i r o s t r i s to behind the poste- 

 rior margin, concealing much of the basioccipital. 



The mandibular ramus is strongly curved, and very convex externally, less 

 so internally. The vascular foramina are very large externally, and very much 

 reduced in size on the inner face. The coronoid process is strongly elevated, 



[April, 



