2 22 PATAGONIAN EXPEDITIONS: ZOOLOGY. 



ered beyond a shadow of doubt that the differences are not due to sex or 

 age. 



Diplolcemjis bibrouii is easily distinguished by the larger scales on the 

 head. The difference is particularly striking in the scales covering the 

 loreal triangle, the space between the suboculars and supralabials, and the 

 series between the lower labials and the malar series. The nostril also 

 appears nearer the rostral, but this is probably partly due to its larger size 

 and the larger, hence fewer, scales between it and the rostral. 



Where we have to do with scales so reduced in size as in this genus it 

 is difficult to establish a scale formula which is not breached by one or 

 more specimens. It is therefore noteworthy that in the whole series only 

 one D. bibronii has a scale interpolated between the first lower labial and 

 the first chin-shield, a condition found in all the D. darwinii before me, 

 while in all the other specimens of D. bibyonii these shields are in contact. 

 In the latter, moreover, the tail is also proportionally shorter and the toes less 

 elongate, though the last mentioned character is subject to considerable 

 variation. 



The difference in coloration, which is quite striking and equally charac- 

 teristic of the adult and the young specimens, is absolutely coincident 

 with the structural differences and even more noticeable. It is not neces- 

 sary to describe these differences here, as they are very well brought out 

 in the original descriptions by Bell, as well as in the figures accompanying 

 them. 



All that Hatcher says about their occurrence in Patagonia is that they 

 are found "about margins of small salt lakes." It is probable, however, 

 that they were collected not far from the Santa Cruz, or from the coast. 



DlPLOL^MUS DARWINII Bell. 



1843. Dipiolcsmus darwinii Bell, Zool. Beagle, Rept., p. 20, pi. x (type 

 locality. Port Desire, coast of Patagonia; types in Brit. Mus.; Dar- 

 win, collector). — Boulenger, Cat. Liz. Brit. Mus., II, 1885, p. 126 

 (part: types). — Burmeister, Anal. Mus. Nac. Buenos Aires, III, 

 1888, p. 250. — Diplolmnus darwini Koslowsky, Rev. Mus. La 

 Plata, VII, ii, 1896, p. 448 (Sta. Cruz ; Chubut ; Rio Negro ; Neu- 

 quen). — Andersson, Oefvers. Vet. Akad. Foerh. Stockholm, 1898, 

 No. 7, p. 460 (part : Cerro Toro, South Patagonia). 

 Apparently this species lives with the foregoing "about the margins 



