''°l80o!''] PROCEEDINGS OF THE NATIONAL MlJ.sElI.M. 623 



and Slotted in yontli, bnt this character tlisappears except on the ante- 

 rior dorsal ip<;ioii of the latter species, where it is tVeipiently letaiiied. 



The species are distril>nted as follows : 



Ke^Mons— Eastern, />. ronNtrictor : Austroriparian, li. vonatrirtur^ li. 

 tlagcUiforme : Central, B. constrictor, li. faniatnm ; Pacilic, //. con- 

 strictor, 11. Jhi(/clli/orme, li. ta'tnatum, li. lateralc ; Sonoran, /.'. flatjelli- 

 forme, B. .semilineatnm, B. piccum, />'. schottii, li. lateralc, B. ornatum, 

 li. tfvniatum : Mexican, Ji. nientorariuni. 



The number of rows of scales is very constant. Apparent excep- 

 tions are referred to nnder the liead of li. lateralc. The nninher of 

 labial scuta is very constant excei»t in the Calilornian representatives 

 of the B. constrictor. Tiie small inferior preocular plate is very con- 

 stant in liascaniuin, its oidy absence beinji' noticed in a very few spec- 

 imens of the Californian form o\' B. contitrictor. The teniporal scales 

 are always normally 2-2-2, and rarely vary from it. 



The anterior and post«jrior parts of the body are frequently differ- 

 ently colorecl in this j^enus. This is especially the case with the B. 

 Jliitfclli forme, Ji. semilincatinn, an<l />'. ornatum, where the jxisterior re- 

 gion is paler than the interior and hutkin^ in the i>attern. In the B. 

 constrictor the transition from the black to the ;;reen variety is first 

 seen in fadinjr out of the black on the tail and i)osterior part of the 

 body. 



As regards the 8tri[)ed forms, wo have evidence how the young dilfer 

 from the adult in the B. semilineatum and tlie li. ttvniatnm. In these 

 the tendency to form distinct wider bands is stron;^''er tii:in in the adult, 

 where ihey are snbdivided and more or less obliterated. Thus the 

 young of both these forms resemble niore the />'. lateralc than do (he 

 adults. We may then regard the B. laterale as representing a primi- 

 tive form for this series. The primitive form for B. flaf/elli/orme and B. 

 constrictor was probably a cross-banded foiin. but no such spt'cies is 

 known. In this respect the last named species resemble tiiose of the 

 genus Dry mobius, where the young are cross banded or spotted. Some 

 Drymobii are known when^ the adidts are cross-spotted. 



The remains of a JJascanium were found by Mi-. <". M. \\ hcatley in 

 the bone cave at Port Kennedy, rennsylvania. whi<li tiirnislicd so 

 many species of extinct nninunalia. 



Basc^iniuin constrictor Lint). 



l?il. :iii<l (iir(l.,Ciit. Serp. N. Viiuir.. IH.MI, p. <(:{; C'opi", CluM-k Li>«r Hatr. K«^pt. X. Aiii.t.. 

 1S7.-.. p. 4(t. 



rohihirciiiintrictor l,iim., S\ r^i. N;ii., i, \1 ><■■•, p :?>>'.'; ftiiwim. I.iiin. ^y.-.!. N;ii ., Ml. i, iii, 

 17-^8, p. IIO'J; ll;irl:in,.l«)iirn. Ac:nl. I'iiil;i., \ . 1M-J7, i>. :M-'; .Schli-j;. Khm. Pliy.-*. S.-rp., 

 \X\7, p. 1:5:5, ri. v. Figs. ;{-4 : StortT Report Kept. .Mass., lt<39, p. C25. Hoil)ro.>k, N. 

 Aiiier. Ilerp., in, 184'.'. p. .'>.'>, PI. Xl : Tliompson, Hi-.t. V«Tiiioiit.f"'l'2. p. 117 ; I»«kay, 

 New York Fauna, Kept. 184*2, p. :5.'>, PI. x, Fij;. -'<•: (Jarni.ui, Meiiioirh Mua. fmiip. 

 Zool., Ciinhriilfio. vm, l'>i^^, p. M7. 



IlicrophiHroiitfrirlor lionap.. Fauna Itali< .-i. ii. 1-11. nonien niuliitn. 



