NATURAL SCIENCES OF PHILADELPHIA. 229 



not the temporal fossae roofed over by ossified, or much thickened dermal 

 plates. The families may be thus compared : 



a.. Premaxillary single. 



Temporal fossae not roofed ; tongue squamous papillose 



in oblique series, or squamous. Nostril in plate 



or suture : always a xiphisternal fontanelle Teidae. 



Temporal fossae roofed ; tongue wholly or partially with 



oblique plicae projecting forwards and inwards ; 



nostril on intersquamal suture Lacertidae. 



Temporal fossae roofed ; tongue squamous ; nostril in 



single plate Ecpleopidae. 



/?. Premaxillary double. 



Temporal fossa roofed. Tongue squamous. Nostril in 



a single plate; palatine maxillary laminae dilated ; 



rarely a xiphisternal fontanelle Scincidae . 



Temporal fossa roofed ; tongue squamous. Nostril in 



notch of rostral ; palatine maxillary laminae often 



dilated Sepsidae. 



I do not know the complete characters of the Chalcidae, but they are very 

 near the Lacertidae. The American Lepidophyma, Xantusia and Cricosaura 

 enter the Lacertidae, as here defined, as I have failed to find characters which 

 separate them from this Old World family. The affinity to Zonurus, pointed 

 out by Dumeril, is manifested in the double parietals of the first two. Mancus 

 and Gerrhosaurus enter the same family in all points though the tongue is 

 partially scaly but in Zonurus there are two important exceptions in which 

 it approaches Gerrhonotus, viz : the tongue is papillose, and the posterior 

 limb bounding the clavicular foramen is wanting. Tretioscincus* enters the 

 Ecpleopidae, but presents the peculiarity of a simple clavicle. In a species of 

 Brachypus I find the clavicle not always perforate, and in Trachysaurus the 

 foramen is also wanting, although the dilatation is extensive. All these 

 families, except the first, are known to possess serpentiform types ; such 

 are among the true Seines, Siaphus, Hemiergis, Campsodactylus, etc. 

 The last is a degraded form of Mabuia : in the second the articular and 

 subarticular bones appear to be united : the first is, in all respects, typical of 

 the family in its proper characters, as illustrated by the species at hand, 



S. simplexf mihi. 

 Pygopus and Lialis, with simple premaxillary, enter this tribe and are 

 perhaps types of separate families. Whether Aprasia belongs in this or the 

 next is as yet a question; it has some points of resemblance to Amelia.} 



* T. b i f a s c i a t u s, Heteropus Duni. T. castanicterus Cope. 



fS. simplex. Nasals as high as broad, not meeting above rostral : internasal much broader than 

 long, in contact with prufrenal. Frontonasals longest transversely, with an acute inner angle, not 

 touching in front of frontal. Latter elongate cuneiform, three-sided in front. Supraorbitals 

 four, posterior small; frontoparietals large, extensively in contact, occipitals large, long, nearly 

 entirely separated by the interoccipital (which is long as the frontal) and bounded exteriorly by a 

 long exoccipital. 5 superior labials. Transverse symphyscal and mental: 1st pair infralabials in 

 contact, and two following pairs very elongate transversely. Twenty rows scales round the middle 

 of the body, dorsal larger; four rows broader on nape. Three toes on anterior, none on posterior 

 extremity. Color above stee! brown, below dirty yellow: a yellowish occipitonnchal collar. 

 From end of muzzle to vent 3 in. 6 1. Vent to end of tail i in. 6 1. Hab. Australia. 



J An allied genus, which will compel the union of the Aprasiida; with the Pygopidse, is Pletholax 

 mihi, with the subjoined characters : Posterior extremities, no preanal pores. Two pair of su- 

 pranasals, nares between the anterior and first superior labial; one transverse frontonasal. Ros- 

 tral oval, prominent. All the scales imbricated, with two keels and a groove between; no larger 

 abdominal series. P. gracilis is Pygopus gracilis, Schlegel, (Mus. Leyden) to whom I am in- 

 debted for the opportunity of making this description. Occipitals broad, acuminate, as long as 

 frontal and frontonasal. Three supraorbitals, posterior largest, Temporal scales large, keeled. 

 Gulars keeled; one very large symphyseal followed on each side by two transverse labials, and 

 these by two longitudinal narrow labials aud two large infralabias. Sixteen rows of scales. 

 Pale brown, a paler median dorsal band, two scales wide, bordered with dark brown. From Suuth 

 West Australia. 



1864.] 



