CROCODILIANS, TJZARDS, AND SNAKES. 487 



I'l/fiopidw Gray, Cat. Liz., 1815, pp. I, (w. 

 Jprasiadw Gray. Cat. Liz., 1845, pp. 4, 68. 

 lAalhidtr Gray, Cat. Liz., 1845, pp. 4, 69. 



Py<jopodid(V Boulengkr, Aun. Mag. Nat. Hist. (5), XIV, 1884, i>. 119; Cat. Liz. 

 Biit. Mhs., 2d C.I., I, 1885, p. 239. 



According to Bouleuger — 



Tlie promaxillary is single, narrowed, and much produced posteriorly between tlie 

 nasals, in the long-suoiiled lAalls (juite as much as in the Varan idte ; the nasals are 

 distinct; the frontal is single; the pr;c- and postfrontals ai'e in contact, separating 

 the frontal from the orbit; the parietals remain distinct, except in LiaUs; the jugal 

 is rudimentary, tliere being no postorbital arch; a postfrontosquamosal arch is also 

 absent; the pterygoids are widely separated and toothless. The mandible contains 

 only four bones, the angular, supra-angular, and articular having coalesced. The 

 dentition is pleurodont. The teeth are small, numerous, and closely set; in Lialis 

 they are recurved posteriorly, very acute, and swollen at the base, thus resembling 

 those of the Varanidic, whilst in the other genera they do not diverge from the 

 normal pleurodont type, being obtusely pointed and with long cylindrical shafts. 

 The skin of the head is quite free from the cranial ossification and there are no supra- 

 orbital bones. The serpentiform body is destitute of functional limbs ; the fore limb 

 is entirely absent, while the hind pair is visible externally as a scaly flap, most 

 developed in Py(jopus, in which the bones of the limb may be felt more or less dis- 

 tinctly ; when the skin is removed in Fygopus the foot with five ossified toes is seen 

 most plainly, especially in the males; the ischium appears externally us a small spur 

 on each side behind the anal cleft. The sternal apparatus exists in a rudimentary 

 state. The tail is long and fragile. The eyes are rather small, with elliptico- 

 vertical or subelliptical pupil, and not protected by movable lids. The ear is either 

 exposed or concealed under the scales. The tongue is fleshy, papillose, elongate, 

 more or less fully incised anteriorly, and extensible. The body is covered with 

 roundish imbricate scales and the head is more or less regularly plated. Pr:eanal 

 pores are frequently present. 



SYNOPSIS OF genera. 



I. Parietal bones distinct; head with 51 large and symmetrical shields. 



A. Pra-anal pores. 



Scales keeled Py(/opiii< Merrem. 



Scales smooth Crypfodelma Fischer. 



AA. No pra-anal pores. 



Scales smooth ; parietal plates large; two rows of enlarged ventral plates. 



Delma Gray. 



Scales bicarinate Plctholax Cope. 



Scales smooth ; subequal; no parietal plates; ear concealed.. J^rasJaGray. 



II. Parietal bone single ; head covered with small scales Lialis Gray. 



Tbe degradatioual features of Pygopns lepidopus, the type of the 

 genus, are as follows: They have been already described in part by 

 lleusinger,! Cuvier,^ Milller,' and Fiirbringer.^ From Australia. 



Scapular and pelvic arches present; no anterior, and rudimeutal 

 posterior, limbs. 



Scapular arch. — Elements present except interclavicle. Sternum a 

 small longitudinally oval cartilage in contact with coracoid cartilages 



'Zeitschr. fiir organ. Physik., Ill, Ft. 5, p. 489. 



-Regne Animal, 1817, II, p. 56. 



•'Tiedemann u. Treviranus, Zeitschr. f, Physiologie, IV, 1831, p. 221. 



^Die Knochen u. Muskeln der schlangeniihnlichen Saurier, Leipzig, 1S70. 



