4. PIETHOIAX. 5. APRASIA. 245 



Eostral pentagonal ; nostril pierced in the lower portion of the 

 nasal, which forms a suture with its fellow on the snout ; a pair of 

 large plates between the nasals and the praefrontal ; latter seven- 

 sided, a little larger than the frontal, which is also seven-sided and 

 smaller than the parietals ; a band-like plate on the outer side of 

 latter ; two supraorbitals ; a large loreal and four small plates 

 between the orbit and the nasal ; seven upper labials, fourth elongate 

 and situated below the orbit, from which it is separated by a row of 

 small scales ; mental large, triangular ; six lower labials, the first 

 forming a suture with its feUow behind the mental. Fifteen 

 longitudinal rows of scales round the middle of the body. Two 

 enlarged prseanal scales. Olive-green, lighter beneath ; on each side 

 of the back two light, dark-edged longitudinal lines. From snout 

 to vent 80 millim. ; tail 167 miUim. 

 Melbourne. 



4. PLETHOLAX. 



Pletholax, Cope, Proc. Ac. Philad. 1864, p. 229. 



Rudiments of hind limbs externally. Head with large sym- 

 metrical plates. All the scales imbricated, with two keels and a 

 groove between ; no larger abdominal series. No prseanal pores. 



Australia. 



1. Pletholax gracilis. 



Pletholax gracilis, Cope, I. c. 



Pygopus gracilis, CHinth, Zool. Erebus S/- Terror, Rept, p. 10, 



Rostral oval, prominent ; nostril between the first labial and a 

 nasal, which is followed by a second ; one transverse preefrontal ; 

 parietals broad, acuminate, as long as frontal and preefrontal ; three 

 supraorbitals, posterior largest ; temporal scales large, keeled ; four 

 lower labials, the two anterior large, following the very large 

 mental ; gular scales keeled. Sixteen rows of scales. Pale brown ; 

 a paler median dorsal band, two scales wide, bordered with dark 

 brown. 



South-west Australia. 



5. APRASIA. 



Aprasia, Cfray, Ann. Sr Mag. N. H. ii, 1839, p. 331, and in Qrey's 

 Trav. Austral, ii. p. 438, and Cat. p. 68. 



Parietal bones distinct. Tongue rounded and slightly nicked at 

 the end. Ear concealed. Slight rudiments of hind limbs externally. 

 Head with large symmetrical plates ; no parietals. Scales smooth, 

 cycloid, imbricate, those on the beUy scarcely enlarged. No prseanal 

 pores. 



Australia. 



