AlKlNSON : Rl.l'llI.ES OK Al.I.KdllKXY CoUNTV. 155 



Also a rare species. A small specimen of this species was collected 

 on the banks of the Monongahela River above McKeesport, August 

 27, 1S98. Soft -shelled turtles are caught along the river occasionally, 

 but no specimens are at hand to show to which species they belong. 

 Aspidonectes spinifer is a common turtle along the upper part of the 

 Monongahela River. 



Family CHELYDRIDiE. 



This family is represented by one genus in Allegheny County : 

 Chelydra. 



Genus Chelydra Schweigger. 



27. Chelydra serpentina (Linnaeus). Snapping-turtle. 



This is a common species in the rivers, and is also found in the 

 ponds and large creeks. It is highly prized as an article of diet. 

 Sometimes it attains a great size ; a specimen caught at Erie in June, 

 1900, weighed forty-two pounds. 



Family KINOSTERNIDiE. 



Key to local genera of KinosU'niidce. 

 Plastron not nearly filling up the opening in carapace ; anterior lobe slightly movable. 



Aroviochelys. 

 Plastron almost filling up the opening in the carapace ; anterior and posterior lobes 

 movable. Kinosternon. 



Genus Aromochelys Gray. 



28. Aromochelys odorata {^0^,(1). Musk-turtle. 



Several specimens of this species have been taken along the rivers. 

 There is a small specimen in the Museum collection. Avhich was taken 

 in an ice-pond near Etna, June 17, 1900. 



Genus Kinosternon S])ix. 



29. Kinosternon pennsylvafiiatm (Gmelin). Mud-turtle. 



This species appears to be very rare in this locality. A small speci- 

 men was taken in a pond near McKee's Rocks, May 29, 1900. Prob- 

 ably the lack of suitable ponds is responsible for the scarcity of this 

 species here. 



Family TESTUDINIDiE. 



Key to Local Genera of the Testudinida. 

 .•\. Plastron, bridge, and carapace firmly and immovably sutured together. 



B. .'Vlveolar surface of upper jaw with a median ridge. CInysetnys. 



BB. Alveolar surface of upper jaw without a ridge. 



