35. IGUANA. 



191 



I regard this form as merely a varietj- of the preceding, the only 

 difference being the development of two or three of the median 

 scales of the snout, behind the line of the nostrils, into conical, soft 

 tubercles. In adult males these tubercles are more developed and 

 form a small crest, but in some females the crest is quite indistinct, 

 and the young are not always to be surely distinguished from 

 I. tuhercuJata. I must also observe that some of the specimens 

 ({, s, t) which I have referred to the latter show clearly in the 

 scaling of the snout a tendency towards the rhinolopha form, 

 so that there is a gradual passage from the one to the other. 

 The other character which has been given as diagnostic, viz. the 

 number of scales in the dorsal crest (from its origin on the nape to 

 the base of the tail), is hardly of importance. Altliough there is 

 usually a lesser number of these scales in /. rJiinoJojiha than in 

 7. tnhercidata, this distinction is not a reliable one : our series of 

 specimens show variation between 47 and GO scales in the latter 

 form and between 44 and 5S in the former ; and it is remarkable 

 that the specimens of /. tuherculata with subconical scales on tlie 

 snout give the highest numbers (G2 to GO), whereas the specimen 

 of /. rhinolopha in which the rostral tubercles are the least de- 

 veloped has, on the contrary, the smallest number (44). 



Central America and West Indies. 



2. Iguana delicatissima. 



Iguana delicatissima, Gray^ Cat. p. 187. 

 Iguana delicatissima, Ldur. Syn. Itepf. p. 48. 

 • nudicollis, Ckv. U. A. 2ud ed. ii. p. 4o ; Giier. Icon. li. A., Repf. 



pi. xi. fig. 1 ; Diim. k.^ Bibr. iv. p. '20S ; Cope, Proc. Am. Phil. 6'oc. 



1809, p.l'ja 

 Amblyrhvnchus delicatissimus, Wagl. Syst. Amj)h. p. 148. 



Differs from /. tahcrculata in the following points : — Scales on the 

 occiput more or less conical ; no large shields below the tympanum, 

 but a regular series of large chin-shields, parallel with and much 

 larger than the labials, on each side ; only a few triangular com- 



