NO. 1437. A NEW LIZARD FROM MEXICO— STEJNEaER. 567 



Dimensidiix. 



mm. 



Total length 104 



Tip of tiiiout to vent 76 



Vent to tip of tail - -« 



Tip of snout to tip of postorbital ])oss 16 



Tip of snout to tip of extreme teni])oral scale - - 25 



(ireatest width of head 28 



Foi'e leg ■lO 



Hind leg 53 



The female {^o. 8<i()lo; sumc loctility and orioin) is smaller (.-^iioiit to 

 rent B-t mm.), hut ai>r(M\s in all particulars with the male, except that 

 the tail is shorter and not swollen at base and without postanal shields. 

 The number of scales in a row between lowei' labials and subman- 

 dibulars 6 or T; about !♦ poorly differentiated femoi-al pores on each 

 side. 



Remark.^. — It is difficult to say to which of the formerly known 

 Phrynosomas the present species is most nearly related. It has no 

 special affinity to any of them. Of course, the absence of "horns" 

 proper may not be a point of great moment, although the correspond- 

 ing- scutes do not have the appearance of retrograded horns such as 

 in some forms of Pliripioxonia donglass/l. With the latter our new 

 species has the greatly expanded supratemporal region in common, 

 but otherwise they show no relationship. The position of the nostrils 

 is nearly exactly the same as in Phrynosoina orhieulare^ but there the 

 similarity ends. The scutellation of the throat reminds one of Phry- 

 nnsohia cornnfKiii^ and as this also is the only other species which has 

 an orbito-temporal, or postorbital, ridge, though much less developed, 

 it may be that it is to this highly spinous and manydiorned species that 

 our hornless and nearly spineless novelty has any real affinity. 



The most unique feature of our species is the enormous vertical 

 expansion of the lower jaw. to which there is not even a faint approxi- 

 mation in an}" of the hitherto known species. 



