222 BULLETIN 58, UNITED STATES NATIONAL MUSEUM. 



parieto-fronto-parietal " is the interparietal; and his fronto-parietals 

 are the true pariotals." 



The digits also show peculiarities which make it inadmissible to 

 incorporate this genus with the typical Lygosoma. The claws appear 

 to be retractile, as in the genus RisteUa, though not within a single 

 shield as in the latter, but between a large upper and a lower shield.^ 

 The digits, moreover, are not covered above with plates, but with 

 imbricate alternating scales on each side of the middle line. 



Lygosaurus, so far as recorded, is a genus peculiar to the Riukiu 

 Archipelago, and does not seem to possess any known near relative. 

 Among the skinks reported from the adjacent countries it stands 

 quite isolated. At present one can only suggest that possibly in the 

 future Formosa may prove to possess some related form. It should 

 be noted, however, that Lygosaurus does not seem to belong to the 

 Himalayo-Chinese fauna. Various points in its structure recall 

 south Indian forms rather than any genus or species pecuhar to the 

 northern mountains. 



LYGOSAURUS PELLOPLEURUS <• Hallowell. 



Plate XVII, fig. 3. 

 1860. Lygosaurus pclloplcurus Hallowell, Proc. Phila. Acad., 18G0, p. 496 (type- 

 localities, Amami-o-sliima and Okinawa, Riu Kiu Archipelago).— iyi/(/o- 

 soma pellopleurum Boulenger, Cat. Liz. Brit. Mus., Ill, 1887, pp. 319, 

 512 ("Loo Choo Islands"); Proc. Zool. Soc. London, 1887, p. 147, pi. 

 XVIII, fig. 2d ("Loo Choo Islands," Pryer collection). — Okada, Cat. 

 Vert. Japan, 1891, p. 70 (Amami-o-sbima; Okinawa shima). — Fritze, 

 Zool. Jahrb. Syst., VII, 1894, p. 860; authors' separate, p. 11 (Okinawa).— 

 Brown, Proc. Phila. Acad., 1902, June 11, p. 185 ("Loo Choo Islands").— 

 Lygosoma (Homolepida) pellopleurum Boettger, Offenbach. Ver. Nat- 

 urk. 33-36 Ber., 1895; p. 107 (Okinawa shima). 

 « Boulenger offers a homology of the cephalic shields somewhat different from the 

 above (Proc. Zool. Soc. London, 1887, p. 148, footnote), inasmuch as he regards the 

 posterior frontal as an azygous fronto-parietal, and the parietals as split up into an 

 anterior (my fronto-parietals) and a posterior pair. I can not follow him in this. 

 In Science College Museum No. 4 (the one here figured, fig. 193) the suture between the 

 anterior and posterior frontals is obliterated, and so it is in our No. 36527. A single 

 shield formed by a combination of these two would have a striking analogy in the 

 frontal of Chalcidoce ps , from Ceylon (Boulenger, Cat. Liz. Brit. Mus., Ill, 1887, p. 423, pi. 

 xxxvii, fig. la) in which it is "angularly emarginate on each side by the first supraocu- 

 lar." In the nearly related Sepophis, from southern India, (Boulenger, Cat. Liz. Brit. 

 Mus., XII, p. 423, pi. xxxvn, fig. 2a), the frontal is actually split much in the same 

 way as in Lygosaurus, and Boulenger himself in the diagnosis of the genus speaks of 

 "two frontals." In this genus "fronto-parietals," much in the same relative position 

 as in Lygosaurus, are "present," while the interparietal is nearly identical in shape 

 and relation. 



bl have no specimen of Ristclla. The arrangement of Ihe claws is described by 

 Boulenger (Cat. Liz. Brit. Mus., Ill, p. 357) as follows: "Claws <'ompletely retractile 

 in a large compressed sheath formed of one large scale cleft inferiorly." Stoliczka 

 first called attention to this character (Journ. Asiat. Soc. Bengal. XLI, Pt. 2, 1872, 

 p. 129), but indicates "retractile claws lying between two terminal enlarged shields." 

 cFrom tteAAos, blackish; itXEvpd, side. 

 d Reproduced in this work on Plate XVII. 



