HOMBRONIA UNDOSA. 241 



SYn. — Eomhronltt undosa, Grd. in Proc. Acad. Nat. Sci. Philad. November, 1857. 



Descr. — A specimen, four inches and three-fourths in total length, 

 gives about two inches to the head and body, making the tail longer 

 than the two former regions combined. The body and neck are sub- 

 quadrangular and depressed ; the body being broader than deep, and 

 the neck deeper than broad. The head is depressed also, and sub- 

 quadrangularly pyramidal. The tail is subconical, stoutish, tapering. 

 The limbs are moderate; the anterior pair, when bent forwards, stretch- 

 ing a little beyond the auricular aperture. 



The rostral plate is somewhat elevated, and subconical. The nasals, 

 subtrapezoid in shape, are almost entirely lateral, giving an opportu- 

 nity to the odd, subrhomboid prefrontal to come into contact with the 

 rostral, and to occupy exclusively the internasal space. The postfrontals, 

 individually smaller than the prefrontal, and like it subrhomboid, are 

 likewise separated from each other by the anterior obtuse angle of the 

 vertex plate. The latter is elongated, subpentagonal, lanceolated, 

 its posterior acute angle engaging between the parietals, which are 

 contiguous upon then- middle and subconvex margin. The middle occi- 

 pital is moderate, spear-shaped, equally engaged between the parietals 

 in front and the latero-occipitals behind, so as to be entirely inclosed 

 by these two pairs of plates. A small pair of postoccipitals may still 

 be recognized from amongst the adjoining scales, contiguous upon the 

 middle line of the occiput, hence diverging sideways, where they meet 

 an elongated and moderate temporal shield, which extends to the orbi- 

 tal chain, adjoining, by its upper edge, the latero-occipital, and beneath 

 a few subrhomboid, inferior temporal shields. There are five supra- 

 oculars ; the second and third largest ; the first nearly equal to the 

 fourth ; the fifth being the smallest ; the latter is contiguous to the 

 latero-occipital plate, together with a portion of the fourth ; the rest 

 of the fourth and the third altogether, are contiguous to the concave 

 margin of the parietal, whose anterior angle manages to thrust itself 

 as far as the second supraocular. The first and second supraoculars 

 are contiguous to the vertex plate, which sends an angular projection 

 to the outer series of supraoculars or supraciliaries, thus preventing 

 the first supraocular to come into contact with the postfrontal. The 

 supraciliaries are eight or nine in number, subquadrangular in shape, 

 and diminishing in size posteriorly, and extend from the postfrontal 

 to the posterior or fifth supraocular. A narrow, elevated postnasal 



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