Dr. W. Peters on Taphrometopon lineolatum. 483 



the longer teeth, because the two small ones before them were de- 

 tached. 



The nine palatine and fourteen pterygoidal teeth are still smaller, 

 decreasing in size from the front palatal tooth. It is therefore very- 

 fortunate that Brandt's name has the priority, as neither Bibron's 

 " Monodiasf.ema" nor Dumeril's " Chorisodon " would be very suit- 

 able appellations for this form. The lower jaw has on each side 

 eighteen teeth ; they increase very rapidly from the first to the fourth, 

 which is followed by fourteen smaller ones. Bibron counts twenty- 

 five ; I might have found the same number, or more, if I had rec- 

 koned the changing teeth on the inner side. The form of the trans- 

 versal and pterygoidal bone is the same as in Coelopeltis, and not as 

 in Psammophis {moniligef). 



I can hardly add anything to the external description given by 

 Lichtenstein and Bihron. The front part of the frontal (vertical) 

 plate is either straight, or it forms a very obtuse angle ; the loreal is 

 curved a little (see fig. 2) ; and all the specimens have nine upper and 

 ten lower labials. One specimen has 192 abdominal scuta and 103 

 pairs of subcaudal scales; the second 189 abdominal scuta and 90 

 pairs of subcaudal scales ; the third 189 and 99. All have the anal 

 plate divided, and seventeen longitudinal rows of scales. All have 

 four large dark olive-coloured bands and a smaller middle one on the 

 head. In one, all four bands continue to the end of the tail ; the 

 second shows, as described by Bibron, no lateral bands, but three rows 

 of small dark spots on the dorsal part ; and the third has neither 

 lateral nor dorsal strokes, the head-bands being lost on the neck. 

 One of them has the lips and the under part of the head yellow, and 

 without any spots ; in the two others the labials and the chin are 

 dotted with black. All have the middle of the abdominal scuta 

 dotted with black, and a black longitudinal stroke on their external 

 parts, which forms on each side an uninterrupted line to the end of 

 the tail. The rest of the under side is yellowish, but appears to have 

 been during life of a red colour. 



A. B. C. 



Total length r-065 1"-115 l™-065 



Length of tail -28 -25 -27 



of head -022 -024 02.5 



Distance of eyes -006 '007 -007 



Breadth of head behind .. 0-010 '010 0-010 

 Greatest breadth of body.. 0-012 '015 0-014 

 The largest specimen contained in its stomach three species of 

 lizards, viz. Phrynocephalus helioscopus, Pallas, Eremias velox, Pall., 

 juv. {vittata, Eversmann), and Eremias variabilis. Pall. 



Conclusions. — 1. Chorisodon sibiricum, Dum. & Bibr., does not 

 come from Siberia properly so called, but from the sandy deserts of 

 Central Asia, around Lake Aral and the Caspian Sea. 



2. The row of unfurrowed maxillary teeth is not interrupted by a 

 diastema. 



3 . Chorisodon is closely allied to Coelopeltis ; it would therefore 

 be most unnatural to separate them into two dilFerent famiUes. 



4. The name Chorisodon sibiricum (date 18.54) must be rejected, 



