186 BtJLLETiN 34, UNITED STATES NATIONAL MUSEUM. 



Gular fold well marked; costal folds fourteen, not continued on back 

 or abdomen. The limbs, and especially the digits, are slender; appressed 

 to the side, they fail to meet by the length of the fingers. The form of 

 the body is slender and cylindrie, and the width of the head enters the 

 total length to the groin seven times. The tail is, as in A. luguhris, 

 equal to the head and body in length, cylindrical, slender, and slightly 

 compressed at tip. 



The thumb possesses a short phalange, but no part of it is free, as in 

 A. luguhris; on the other hand, all the phalanges of the other toes of 

 both feet are more slender than the A. luguhris, and the distal ones 

 distinctly truncate and slightly emarginate, with dermal thickening 

 below tip. All are quite free. Number of phalanges, 1-2-3-2, 1-2-3-3-2, 



Coloration. — Sides and nape greenish-gray; top of head and dorsn] 

 region behind in the form of a serrate band, with the tail, black; below 

 yellowish-brown; limbs black above, brown below; inferior regions un- 

 spotted. 





i 



K^ m if\. 2 6 7 



1 4 3 5 



Fig. 45. Autodax ferreus. No. 6794. FortUmpqua; I, f. 



Measurements, in inches. 



Inchea. 



Length, axial, from snout to rictus oris 42 



Length, axial, from snout to axilla. 70 



Length, axial, from snout to groin 1.75 



Length, axial, from snout to end of vent 2. 



Length, axial, from snout to end of tail : 3. 65 



Length of fore-limb .5 



Length of fore-foot 2 



Length of hind limh 55 



Length of hind foot 20 



Width of hind-foot sole 11 



Width of head at rictus oris 28 



Width of body at middle 24 



Width of body at sacrum 2 



The maxillary bone displays the same sudden decurvature anterior to 

 and below the orbit which the A. luguhris does, but it is less marked ; 

 in consequence, the commissure of the mouth is less sinuate. The long 

 mandibular and maxillary teeth, while of similar structure, are less de- 

 veloped. Perhaps larger specimens of this species may be found where 

 they may be larger, as in small specimens of A. luguhris they are nearly 

 similar in proportions. 



Though nearly allied to the A. luguhris, the present species will never 

 be confounded with it. It is a much weaker form, anl does not display 

 the characters of the cfenus in so striking a degree. The form of the 



