%9T''] PROCEKUINGS OF THE NATIONAL MUSEUM. C83 



Ancistrodon piscivorus Lacdpi'ile. 



Cope, Proc. Acad. Phila., 185'.), p. :}:!(); Check List Hafr. K.<pt. N. Amor., 1^7.-,. ,,. :{4. 



Crotalus piscivorus Lac6pt-cle, Serpens ii, 1787, p. ■\-2\. 



Scyialiis pi!icivonifi Latieille, Hist. Nat. Ki-ptiles iii, |,-(il, p. u;;!; Jiainliu Iliat. 



Kept. V, 1H0;5, p. :544 ; Harlan, Me.l. Pii.vs. K.-s.. I-:!.',, p. l-«t. 

 J\'atrix piscivorus Mcrreiu, Tentainen, 18"i0, p. i;U. 

 Tritionoccphalun piscivoritH Holbrook, N. Amor. Heij). iii, \K\-2, p. :\\, V\. 7; Dimi. et 



Bibron, Eip. Geu. vii, 18r)4, p. 141)2; Jan, Icim. (Jen. Oti.l. ii. IC, i\ . Ki._r. \ -'>-.\, 

 Toxicojjliis piscivorus Bd. and Gird. Cat. 1853, lit. 

 Coluber aquativus Shaw, Gen. Zoiil. in, 1802, p. 4'2.''i, PI. 3, fmm C'ateNliy "\Vat«T 



Viper," Cand. ii, PI. A'A, 17.')4. 



The Anstroriparian region. 



In some specimens froin western Texas the sn])erior labial jdaU'.s have 

 a slight anterior position at the expense of tiie si'cojid, w hicli is soiiu'- 

 what narrowed, especially toward tlie labial border, in one sju'cimcn 

 (No. 822) this plate is a triangle with the apex downward, which does 

 not reach the labial border. In another it enters the border l»y a nar- 

 rower edge than in typical forms. The character is thns variabh'. The 

 same disi)lacenient of the labials brings the fourth labial into tin- Imrdi-r 

 of the orbit by a short edge in some specimens, but this charactfi- i.s also 

 (piite inconstant. On such specimens Baird and (Jirard proposed their 

 To.vie<>2)his puf/nax, but under the circumstances the fitiiii docs not swux 

 to be distinguishable. 



In the young of the Ancistrodon piscivorus the colors are brighter, 

 the colors more contrasted, and the pattern therefore more distinct. 



Ancistrodon contortrix Linn. 



Bd. and Gird., Cat. Serp. N. Amer., 1853, p. 17: Copp Cheek List B.itr. Kept. N. 



Amor., 187'), p. 34. 

 Boa contortrix Linn, Syst. Nat., ndfi, I, i>. 373; <lo. >yHt. .Nat. Kd. 13. 17— i. IM. iii. 



p. .O&Z. 

 Ankistrodon mokcson Pal de Beauvois, Trans. Amer. Philos. Soc. n , 17U".t. p. S-l. 

 Cenc/i; (s HioAt.vt»)( Dandin. Kept, v, 1KI3. p. 3.'')8, PI. 40, Fig. 3; Harlan Unix . I'liys. 



Re.s., 1835, p. 1-28. 

 Scijtalus cupreus Kafncsqne, Amer. Journ. Arts Sci., 1834, i, p. <> ; Harlan, p. i:U). 

 Tritjonoccphahis ceiichris iiclAcsr., Ess. 8. la Pliys. des Scrpent.s, II. 1H37, 5.''>.1, I'l. 20. 



Figs. 10-11. 

 Trigonocephal us contortrix Holbrook, N. Amer. Herpetol. ill, l^J-J, p. 30, I'l. .- ; l)um<«- 



ril et Bibron Erp., Gen. vii, 1854, p. 1404 ; J.tn. Icon. (Jen. Olid., ii, 4(i, v. Fig. I. 



Eastern and Anstroriparian regions; extending eastward to o^Mitral 

 iNIassachusetts. 



In eleven specimens six have the superior labials S-S, two have them 

 7-8, and three have them 7-7. The reduction to .seven may be regard.-.l 

 as abnormal, since in that case there is generally irregularity. It 

 arises sometimes from the fusion of the .seveiitii and eightii plates, and 

 sometimes from the exclusion of the sixth or seventh from the labial 

 border by contraction below. In the latter ease the plate becomes sub- 



