1. HELODERMA. 301 



1. HELODERMA. 



TracLyderma {no7i Latr.), Wicgm. Isis, 1829, p. 421. 



Heloderma, Wiegm. I. c. p. 624 ; Wayl. Syst. Amph. p. 164 ; Wiegm. 



Herp. Mcx. p. 23; Dim. ^- Bibr. iii. p. 499; Gray, Cat. p. 14; 



Bocourt, Miss. Sc. Mex., Rept. p. 290. 



Anatomical and Physiological : Troschel, Arch. f. Nat. 18.5.3, 

 p. 294, pis. xiii. & xiv. ; Sinnichrasf, Arch. Sc. Plnjs.-math. xix. 1804, 

 p. 45; Katip, Arch. f. Nat. 1805, p. .33, pi. iii.; Cope, Proc. Ac. Philacl. 

 1869, p. 5 ; Oervais, Journ. Zuol. 1873, p. 453, pi. xii. ; Sumichrast, C. R. 

 Ac. Sc. Ixxx. 1875, p. 676 ; Bocourt, I. c. p. 299, pi. 20 G ; Sumickr. Bull. 

 Soc. Zool. France, 1880, p. 178 ; Fischer, Verh. Ver. Hawh. v. 1882, p. 2, 

 pi. iii.; Shi(fddt, Amer. Nat. 1882, p. 907; Bouleng. Proc. Zool. Soc. 

 1882, p. 631 ; Fayrer, cod. loc. p. 632; Mitchell 4" Rcichert, Med. News, 

 1883^ and Science, i. 1883, p. 372. 



Ear exposed. A giilar fold. Digits with a series of transverse 

 lamellte inforiorly. Upper surfaces uniformly tubercular ; abdo- 

 minal scales flat, juxtaposed. Labial shields present. 



Mexico^ 



1. Heloderma horridum. 



Heloderma horridum. Gray, Cat. p. 14. 

 Hernandez, Hist. Nov. Hisp. p. 315. 

 Trachyderma horridum, Wiegm. Isis, 1829, p. 421. 

 Heloderma horridum, Wiegm. Isis, 1829, p. 624, a7id Herp. 3Iex. 



p. 24, pi. i. ; Dum. S; Bibr. p. 499, pi. xxxvi. ; Bocourt, Miss. Sc. 



Mex. p. 297, pi. xx. e. hgs. 1-12 ; Giinth. Biol. C.-Am., Rept. 



pi. xxvi. 



Head depressed ; snout short, broadly rounded ; lips thick, 

 arcuate, the lower much swollen ; nostril large ; eye small, with 

 very thick lids ; ear-opening elliptical, vertical, slightly oblique ; 

 chin-groove strong; gular fold well marked. Body elongate, rather 

 depressed. Limbs moderate ; claws strong, of the fingers much 

 longer than of the toes. Tail cylindrical, tapering, about as long as 

 the body. Upper surface of head covered with large, convex, irre- 

 gular, bony tubercles ; rostral broad, pentagonal ; nostril between 

 four plates, the largest inferiorly ; a pair of large intern asals between 

 the two pairs of anterior nasals ; ten or eleven upper and about 

 twelve lower labials ; mental small, subtrapezoid ; chin with large 

 polygonal |)latcs ; throat with round or oval convex tubercles. 

 Body and limbs covered above with subequal round convex tubercles 

 8e])arated by a granulate skin : about thirty-five tubercles across the 

 middle of the body. Abdominal scales flat, subciuadrangular, longer 

 than broad, in about fifty-five scries between tlie gular fold and the 

 pra\anal region, and about twenty across the middle of the belly. 

 Caudal scales subequal, tubercular above, flat and subquadrangular 

 inferiorly, arranged in rings. Blackish brown above, sixjtted with 

 yellow, the latter colour sometimes forming regular rings round the 

 tail. 



