^Tssn!''] PROCEEDINGS OF THE NATIONAL MUSEUM. GSl 



Liodytes allenii G;irmuii. 



Cope, Proc. Amer. PLilos. Soc, 1880, p. 49"). 



HcWcops allenii Garuian., Proc. Bost. Soc. Nat. Hist., 1874, 9-i; Cope, Chock List Bat. 

 Kept. N. Amer., 1875, p. 43. 



Florida only. 



NATRIX Lanrenti. 



Specimen Syuopsis Reptilium, 1768, p. 73 ; Bonaparte, Fauna Italica, 1840, pp. 172, 173; 

 Cope, Proceeds. U. S. Natl. Mns., 1888, p. 39:^. Tropidonolus K\\\\\, Isis voiiOkeu, 

 182(), p. 205; Boie, loc. cit., 1827, p. ;'L8; Wagler, Systenia, 1830, p. 179; Sclilegel, 

 Physioiiomie des Serpens, 1837, 296; Dnmcril et Bibron, Etp. Gdneralc, vii, pp. 

 549-724, 1854; GUnther, Cat. Brit. Mus., 1858, p. 59; Nerodia Bd. and Gird., Cat. 

 Rept. Serpents, 1853, p. 38; Ecgina Bd. and Gird., loc. cit., p. 45. 



Teeth generally longer on the posterior than the anterior parts of the 

 maxillary bone, ungrooved. Two internasal, two prefrontal, and two 

 nasal scntaj one loreal ; parietals distinct. Anal plate divided. Scales 

 keeled 5 scale-pits double. Gastrosteges well developed, not angulated 

 or keeled. 



This genus is widely distributed throughout the northern hemisphere, 

 embracing numerous species in North America and in Eurasia, but is 

 ' wanting on the Pacific district of the former. < n the American con- 

 tinent a single species, N. rliombifer Hallow., extends as far south as 

 Vera Cruz from its North American range. 



I flntl twelve well distinguished species in North America, M'hich are 

 characterized as follows: 



I. Temporal scuta 1-2 or 3 ; parietal scuta normal. 

 a Oculars 2-2 ; scales in nineteen rows. 



Smaller, muzzle wider; three hlack stripes above ; four brown ones below. 



X. leheris. 



Larger, muzzle narrower ; no black bauds above ; two, sometimes three or four, 



iini^)ert'ect bauds below iV. (jrahanin. 



Muzzle short; brown above with a broad median baud ; below yellow, with 



two rows of spots 'N. riglda. 



aa Oculars 1-2; scales in tv>'euty-oue rows. 



Superior labialseight ; head elongate ; brownish yellow, immaculate. i\". tista. 

 aaa Oculars 1-3; scales in 19-21 rows. 



Four brown bauds above; a mediau rowof yellowLsh spots below. jY. clarkii. 



Three rows of brown spots above, which may form stripes anteriorly and 



cross-bands posteriorly ; median row of yellow spots below. 



^^. co)i)2)rcssicaiida. 

 A row of lateral spots, often indistinct ; below, uniform ; tail slender, cylin- 



dric X. valida. 



aaaa Oculars 1, 2-3; scales in 23-25 rows. 



Superior labials nine ; preoculars two; spots longitudinal K. hisecta. 



Superior labials eight ; preoculars one ; spots, when present, transverse. 



N. fasciata. 

 aaaaa Oculars 1, 2-3, 4 ; scales in 27-29 rows. 



Eye resting on (usually) one labial ; alterualing wide dorsal and lateral 



spots, connected at angles jV. rhombifcra. 



Eye separated from labials by scnhs; numerous iiurrow cross-bands, 

 sometimes broken X. cyclopiiim. 



