hO 



Itn.lJlTIN :il, |-NITi:i) STATMS NATlONAI. Ml'SKlIM. 



P.I 



1,1 (his Meet ion it is dcsiniltU' to asccitiiiii liow liir cliiiriicti'i-s »li« 



tiii-;iii.siiiii^' iiii(l()iil)ti"<l species full into (lie line ol'sum'ssioiisil eliiuiyes 

 eomnion to iill the species, :is answer to this (luestion would solve an 

 important part ol the inciniiy as t.» tlieoiij,nn olspeeies. We can not no 

 into it exhaustively a( this time, i»ut direct attention to these char- 

 acters in Mie syuoi»lic tahle. The following,' are developmental char- 

 actera wlii(!h distinj,niish known species: (!) The direction of the pala- 

 tine series of teeth; (li) the length of the Itody and tail, as coini)ared 

 with the width of the head, is ;^Mcater in huj^c and old individuals of 

 .1, tiijrhiHin ; ('■',) tlie widening: of the nni/./.le and greater separation nl 

 the external nares ; (1) the spotted as distinguished iroin the uniform 

 coloration. 



Cliaractei's to which no such relation can he assij,Mied: (1 ) Thenumber 

 (»f costal folds, whose iutersi»aces correspond with tlie vertebra- ; (L')the 

 number of phalan^^es. 



IJaird, in the first synopsis of this genus published, enumerates eij;ht 

 species; (Jray in l.S.'d) eataloj;ues ten, after we exclude some species of 

 othei' jicnera erroneously included. Dumeril, likewise^ iiudndin;; species 

 of other j;cnera, gives live true And)lystoma'. llallowell, IS.'tS, increased 

 tlu! number to sixteen. In my monograph of this genus, ]»ublished in 

 1S(J7, the si)ecie8 described numbered eighteen, six new ones being 

 added. Dr. IJoulenger, in the Catalogiu- of the IJritish Museum, second 

 edition, published in 18815, gave the number as .seventeen, including a 

 Siamese species. In the present wmk thirteen species are admitted, one 

 of which is the Siamese species A. iicfsiiiiilis, after the subtraction of 

 nine species placed in the genera ('huniirntus and LhujiKvltipsUH. For 

 the stmly of this genus the collection of the Smithsonian Institution is 

 une(pialed. Probably the second best collection existing, that of the 

 Academy of Xatural S(Meiices of I'liiladelpnia, has al.so furnished its 

 numerous types, and several species mostly described by the late Dr. 

 JMnvard Llallowell. 



SipiOjIlliH llf KpivivH. 



I. .Sui'icM of tuL'tlii'XlLMiiliii'; iiliiii;; II 



u' i'\|(iti;il li>s.sii'i' "f the iiitcriiiil iiiii't',- 



I'll 



of tongiu! ladiatiiij; lioiii its poMti'iior imriion. I'moloid <;l;iiiil 

 foriiiiii},' ail ovoid distinct mass. I'oiir idialaiiKcs in fomtli loc' 



s llnl 



A. ( 'ostal grooves, ton. 

 i(. Voiiicriiic scries, tint 

 Head lii'oad ; width : 



■ 1 to frioiii ; Mni//h' coiitrac 



ted : 



•\t. 



iial ii.'trc; 



closer tlian iiitenial ; iiahiline scrii-s convex haekwards; tail mIioii. 



coniiiressed ; hlackish-hrowii, .ura.v sjiucke I. 

 B. Costal 1,'rooves, eleven. 

 a Vomerine series three. 

 li No, or one iiidistinet plant.-ir liiUcrele, 



J. itdiH 



Middh- s.' 



ru's transverse or concave to lieliind posterior inarj;ins of nan 



width of lieail in specimens of :{ inel 



ics, ureatertliaii one-fonrtli lenijll 



to irroin : in adnlts, 1.7 tin 



l)!ael. 



k ahove, with urav <;r 



OHs-nanil 



.1. 



o/iitciiiii. 



Vhl, 



!■ UU CMlllIlllll Mlicl( J .1 II. 



JSl 



