N 1923 5 ] AMARAL NEW GENERA AND SPECIES OF SNAKES 95 



2 postoculars; temporals, 1 -f- 2; 6 upper labials, 3d and 4th entering the 

 orbit, 5th and 6th very long; 3 pairs of chin shields, the middle larger. 

 Scales smooth, without pits, and showing remarkable peculiarity as follows: 

 15, 16, 17, 18, or 19 rows, the vertebral sometimes only slightly and some- 

 times strongly enlarged transversely all along the body by the fusion of the 

 middle row with 1, 2, 3 or 4 paramedian ones; 1, 2, 3 or sometimes 4 para- 

 ventral rows also enlarged. Ventrals, 153, rounded laterally; anal entire; 

 subcaudals, 36/36 + n. 



Type, adult 9 , no 3002 in the collection of the Instituto de Butantan, 

 sent alive from the locality Villa Bomfim, State of Sao Paulo, Brazil, on 

 February 25, 1913, by Mr. Joao Rodrigues da Silva. 



Total length, 450 mm. + n; tail, 65 mm. -f- n. 



The new genus Heterorhachis is very interesting indeed be- 

 cause it shows characteristics belonging to both families Colu- 

 bridae and Atnblycephalidae. It agrees with the Colubridae in 

 having rather long and slightly diverging pterygoids, and with 

 the so-called Amblycephalidae in having hypapophyses present 

 only anteriorly and no mental groove. It may thus suggest the 

 suppression of the family Amblycephalidae, 1 the different genera 

 of which should be included in a new subfamily of the Colubridae. 



This subfamily, which I should call Dipsadinae, is perfectly 

 characterized by pterygoid usually short (exceptionally extend- 

 ing to quadrate), solid teeth in both jaws, hypapophyses absent 

 in the posterior two thirds of the vertebral column, and mental 

 groove absent. It should include the following genera: 



Dipsas Laurenti, 1768 (type, D. indica). 2 

 Amblycephalus Kuhl, 1822 (type, A. carinatus). 

 Sibynomorphus Fitzinger, 1843 (type, S. mikanii). 

 Aplopeltura Dumeril, 1853 (type, A. boa). 

 Pseudopareas Boulenger, 1896 (type, P. vagus). 

 Heterorhachis Amaral, 1923 (type, H. poecilolepis) . 



Through the genus Heterorhachis, which has rather long and 

 slightly posteriorly divergent pterygoids, hypapophyses present 



i See A. Gunther, Rep. Brit. India, 1864, p. 324. Aiso, G. A. Boulenger, Faun. Ind., 

 Reptiles, 1890, p. 414, and Cat. Sn., Ill, 1896, p. 438. 



2 Fitzinger (Syst. Reptilium, 1843, p. 27) selected the species weigelii as the type of 

 Dipsas, but this was not Laurenti's conception (see Art. 30, II, 3, d, of the Int. Rules of 

 Zool. Nomenclature). 



