276 MEMOIRS ON THE COLEOPTERA 



third longer than the prothorax, inflated near the base, not much nar- 

 rowed behind; surface minutely, sparsely punctured throughout and, 

 posteriorly, becoming reticulate and feebly alutaceous, the apical margin 

 abruptly and steeply beveled and polished, the stria obsolete; striae very 

 oblique and extremely fine, extending behind the middle, the fourth only 

 to the middle, arched at base and joining the excessively fine but entire 

 sutural; outer subhumeral forming an inner concavity along the lateral 

 carina, the inner very oblique, fine and medial; pygidium convex, 

 finely, rather sparsely punctate; prosternum with two long striae, 

 approximate, diverging basally, also diverging anteriorly in about apical 

 third, there forming a large elongate closed loop, which is tangent to the 

 apical margin; intermediate surface nearly flat throughout the length; 

 hypomera flat, closely and rugosely punctate and with very stiff pale setae 

 throughout; anterior tibiae with moderate external spinules. Length 

 2.1 mm.; width 1.25 mm. New Mexico (Las Cruces), Cockerell. 



This is one of the most isolated of our Saprinus species, for 

 there is none other with which it can be associated in any way 

 closely, and its peculiarities suggest some such biological status as 

 that of an ant-guest. The head is very much as in scabriceps in 

 sculpture and in the nature of the unbroken frontal carina, but the 

 prosternum is wholly different, reminding us of that characterizing 

 bigemmeus, as above described. 



Teretriosoma Horn 



The position of this genus in the Histeridae seems to be uncertain. 

 LeConte, Horn, and, in more recent years, Lewis, in the "Biologia," 

 place it after Saprinus, but in the Bickhardt catalogue it is given a 

 place near the beginning of the series and before Ulster; which of 

 these concepts is correct I have no inclination to surmise at present. 

 This genus is more extensive than Teretrius, and its species have 

 usually a stouter habitus and more brilliantly metallic coloration 

 as a rule. The division between the two sections of the pygidium 

 is made generally by a transversely arcuate angulation of the 

 surface, but in sexualis Schf., represented before me only by numer- 

 ous females, there is an acute central umbo forming the division. 

 The following species is allied to chalybcea Horn, but is stouter: 



Teretriosoma pinguis n. sp. Short and broad, very convex, with 

 parallel and feebly arcuate sides, black, polished and with strong blue- 

 green lustre above and beneath, the legs red; head evenly convex, 

 strongly and sparsely punctate, more closely on the obtuse ridge above 

 the more sloping apex; prothorax nearly a third wider than long, sparsely, 

 not coarsely and subevenly punctured throughout; base broadly, feebly 



