MR. A. MURRAY'S MONOGRAPH OF THE FAMILY OF NITIDULARLE. 283 
46. COLASTUS OBLIQUUS. 
Leconte, in Proc. Acad. Nat. Sci. Philad. March 1858, 62 (1858). 
Depressus, ovalis, niger, griseo pubescens; thorace subtilius punctato, antrorsum angus- 
tato, margine angusto testaceo postice latiore; elytris subtilius punctatis, obscure 
rufo-testaceis, limbo laterali postice latiore apicalique nigris, sutura paulo infuscata ; 
antennis nigris; pedibus obscure rufis. Long. 1 lin., lat. 2 lin. 
Habitat apud flumen Colorado in California. 
Variat (immaturus) piceo-testaceus, elytrorum disco ab humeris ad suture apicem palli- 
diore, versus scutellum infuscato. 
Depressed, oval, black, griseo-pubescent. Antenne black. Thorax very faintly punc- 
tate, narrowed in front, the margins narrowly testaceous, more widely so behind. Elytra 
very faintly punctate, obscurely rufo-testaceous, with the lateral and apical margins 
black, the black part widest behind, the suture slightly fuscescent. Legs obscurely 
rufous. 
I have not seen any specimen of the species described by Dr. Leconte under this name ; 
but, from his description, there seems to be little specific difference between it and his 
C. limbatus. He himself says it is of the same size and form, but differs from it by the 
less dense punctuation of the thorax, and by the lateral black margin of the elytra being 
gradually broader from the humerus, and by the base not being margined with black. 
This coloration would carry it to C. infimus, to which, on other grounds, it is nearly allied, 
and would form the transition between it and C. limbatus; but the thorax narrowed in 
front being specially mentioned as a character, and the extent of its narrowing being the 
chief distinction between C. limbatus and C. infimus, I think it most probably a variety 
of C. limbatus. As, however, Dr. Leconte is not in the custom of making species upon 
slight or insufficient grounds, I have preserved the species and given the whole of his 
description, so that the reader may judge for himself. 
From the River Colorado, in California. 
47. COLASTUS TANTILLUS. 
(Leconte, in Agassiz's Lake Superior, 222 (1850).) 
Dr. Leconte has recorded (in the appendix to Agassiz's ‘Lake Superior’) a species 
under this name as having been found on the shores of that lake, but has given no 
description of it there, nor am I aware of his having described it anywhere else. I have 
not seen it, so that I ean do no more than notice its existence. 
The following dichotomous Table may be of service as a rough uds to the determina- 
tion of the species of this difficult genus :— 
More or less shining, with the thorax distinctly punctate . . . . . 1 
| More or less dull. Texture soft or shagreened. . ; 39 
Base of thorax nearly straight and its posterior n nini or "ight 
angled. Anterior tibiz distorted in the males . . . . . 2 (Subg. Cyllopodes.) 
: Base of thorax bisinuate and its posterior angles sealing more or less 
backwards. Anterior tibiz not distorted in males. . . . . . . 7 (Subg.Colastus proper.) 
eae Em 
