194 



BULLETIN 58^ LTNITED STATES NATIONAL MUSEUM. 



1852. Lamprosaurus Hallowell, Proc. Pliila. Acad., t]852 (j). 206) (type, L. 



guttulatus). 

 1871. Plistodon Cope, Sec. and Third Ann. Rep. Peabody Acad., 1871 (p. 82) 



(emendation). 



The characters reUed upon in the genus Eumeces for the proper sep- 

 aration and identification of the species are unfortunately subject to a 

 wide range of variation, at least in some of the species. Such crite- 

 rions as the absence or presence of a postnasal, of one or two post- 

 mentals, the number of scales around the body, etc., are apt to fail 

 when most needed. Yet they are the only ones which the systema- 

 tist has to rely on, and though he may be convinced that he has to deal 

 with separate forms, nevertheless he may occasionally have to fall back 

 on locality. Take, for instance, Eumsces elegans of Boulenger, from 

 China. The only character ])y which I can distinguish it from E. Inti- 

 scutatud, from Japan, is by the absence of a postnasal. Yet, among 



177 ^'^ 



FiG.s. 17(>-178.— Head shielub of Siincid lizards. 176, side view of head of Leiolopisma; 177, 



UPI'ER VIEW OF HEAD OF LEIOLOPISMA; 178, UPPER VIEW OF HEAD OF EMOIA. M, CHIN-SHIELDS; cl, 

 DISK ON LOWER EYELID; C, EAR-OPENING; /. FRONTAL; fn, FRONTO-NASAL; fp. FRONTO-PARIETAL; 



/.interparietal; i7, lower labials; /, loreals; /6, upper labials; /n, mental: n, nasal; nc, 

 NUCHALs; p, parietals; /;/, prefrontal; pn, postnasal; r, rostral; sc, supraciliaries; mi, 

 supranasal; so, supraocular; t, temporal. (All figures enlarged.) 



sixt}— two Japanese specimens examined 1>3' me, five lack the post- 

 nasal on both sides ami two on one sitle. It does not seem to be to the 

 best interest of science to make E. elegans a synon^an of E. latiscuta- 

 tus. Much less would it do to call the five Japanese specimens E. ele- 

 gans and enumerate botli species as occurring together in the island of 

 Hondo. Very likely some of these specimens without postnasals are 

 brothers or sisters of the others- which have this shield. Moreover, 

 what are we to do with those which have it on one side but not on the 

 other? It would probal)ly be a fit case for trinominals were we to find 

 a similar proj^ortion of postnasals ])resent in Chinese E. elegans, but 

 unfortunately we have not sufficient material of the latter to deter- 

 mine the point. The most conservative proceeding therefore is to 

 leave the two forms their binominal nomenclature at least until we 

 shall know the Chinese form better. 



