THE KANSAS UNIVERSITY 

 SCIENCE BULLETIN. 



Vol. X, No. 12.] January, 1917. [^l.Tx^no'". 



The Function of the Supraglenoid Canal. 



BY HERMAN DOUTHITT. 



SEVERAL months ago the writer was discussing with Pro- 

 fessor Williston the presence in Diplocaulus of the supra- 

 glenoid foramen, a structure which has been recognized in 

 nearly all Permian reptiles, and in the Temnospondyli. Pro- 

 fessor Williston stated that he had been surprised to note that 

 the same foramen occurs in the lizards, where its presence had 

 apparently been completely overlooked. He suggested that the 

 writer study its function in the lizard, with the view likewise of 

 determining its function in the early Tetrapoda. 



With this end in view, the writer has made a careful study of 

 the collared lizard, Crotaphytus collaris. Part of the material 

 used was secured from the Dyche Museum of Natural History. 

 I wish here to acknowledge the courtesy of Mr. CD. Bunker in 

 placing this material at my disposal. Fresh material has like- 

 wise been collected, and the arteries injected. 



The supraglenoid canal, or foramen, occurs in two distinct 

 forms. In lizards and Temnospondyli, in most Cotylosauria 

 at least, and in some Thermorpha, as Edaphosaurus and 

 Ophiacodon, its external opening is on the posterior edge of the 

 scapula, at the bottom of the supraglenoid fossa. In the lizard, 

 and no doubt in the other forms, the foramen lies just laterad 

 of the area of insertion of the long head of the triceps muscle. 

 In the lizard, however, there is no fossa. The canal passes 

 from the foramen upward and forward, to open finally upon the 

 inner surface of the scapula. In Crotaphytus and Varanus this 

 canal is of considerable length, the inner opening being well 

 above the middle of the scapula. 



C261) 



