474 BULLETIN UNITED STATES GEOLOGICAL SUHVEY. 



But in order to exhibit the resemblances of the species to each other, 

 a different grouping is necessary. In preparing a suitable one, I have 

 used as a primary character the nun\.ber of ambulatorial setse, which 

 arise from punctures on the ventral segments of the abdomen. 



These punctures are arranged in a row each side of the median line, 

 running backwards from the hind trochanters, as in other Carabidob; 

 in nearly all the species, these rows are formed by two or three approxi- 

 mate punctures arranged transversely on each segment ; but in JV. vires- 

 cens and pallipes the rows are reduced to single punctures on each 

 segment. The further division of the species into groups may then 

 proceed by the form of the elytra and the width of the side-margin of 

 the prothorax, as in the following table. The form and sculpture of the 

 prolonged posterior extremity of the prosternum will also be found use- 

 ful for separating the species in each group. 



TABLE OF GEOUPS OF SPECIES. 



Eows of ambulatorial setse double 2. 



Eows of ambulatorial setse single 3. 



2. Elytra oval, without humeri; episternaof metathorax not longer than 



wide, Sp. 1—3 , a L 



Elytra elongate-oval, with indistinct rounded humeri ; episterna of 

 metathorax more than one-half longer than wide, Sp. 4 — 7 II. 



Elytra oval, with indistinct rounded humeri; episterna of metathorax 

 more than one-half longer than wide; prothoracic side-margin nar- 

 row, Sp. 8— 9 .-..in. 



Elytra more or less truncate at base; humeri distinct; prothoracic 

 side-margin wide, Sp. 10 — 21 IV. 



3. Prothorax moderately narrowed behind, Sp. 22 V. 



Prothorax very much narrowed behind, Sp. 23 „ . . . VI. 



Group l:—ingens. 



In this group, the episterna are short, scarcely longer than wi-de. The 

 elytra are oval, or elongate-oval, oblique and rounded at base, without 

 trace of humeral angles. The wings are entirely wanting, or unde- 

 veloped. The prosternum varies in form, according to species. The 

 side-margin of the prothorax is narrow in N. diversa and inge7is, but 

 wider in ovipennis. The rows of ambulatorial setse of the abdomen are 

 double. 



Three species are known to me, inhabiting the high mountains of the 

 Pacific slope : — 

 Prosternum flattened at tip and margined ; side-margin of prothorax 



extremely fine; color pale brown „ . . . 1. diversa' 



Prosternum prolonged, lanceolate at tip, margined at the sides, but 

 not at the extreme tip; side-margin of prothorax very fine; color 



black 2. ingens. 



Prosternum flattened at tip, slightly declivous, and not margined ; side- 

 margin of prothorax wider; color black » . .3. ovipennis, n. sp. 



