ART. 17. LARVAE OF HOLARCTIC TIGER-BEETLES HAMILTON. 69 



five-eighths the length of the median hooks, and with two setae; 

 median hooks with two setae ; lateral hooks with five to seven setae. 



Measurements. — Length of larvae, 24 to 26 mm., width at the 

 third abdominal segment, 3.2 to 3.4 mm. ; diameter of ocellus 1, 0.42 

 to 0.44 mm., of ocellus 2, 0.29 to 0.31 mm.; distance between ocelli 

 1 and 2, 0.26 to 0.28 mm. ; length of fronto-clypeo-labral area, 2.1 to 

 2.3 mm., width, 2.4 to 2.6 mm. ; length of pronotum, 2.6 to 2.8 mm., 

 width, 4 to 4.3 mm. 



The larvae were collected at Licking Fork, Mokehimne River, 

 California, at an elevation of 2,900 to 3,100 feet, by Dr. F. E. 

 Blaisdell, sr., and Beverly Letcher. 



A single larva of 07niis edwardsii Crotch, the identity of which 

 was questioned, was secured from Dr. F. E. Blaisdell, sr. ; this larva 

 vras collected in the same locality as Omus sequoiarum and seeins to 

 be identical with it (figs. 48, 87, and 122). The pronotum (fig. 

 87) shows a few more setae than that of Omus sequoianim (fig. 85), 

 but the larvae of the later species were observed which had a similar 

 setal plan. 



6. Genus AMBLYCHILA Say. 



Head with ridge on caudal part of frons transverse and continuous 

 with the ridge on caudal part of vertex; latero-clypeus not distinct, 

 fused with the clypeus; anterior margin of the labrum slightly 

 crenulate; ocellus 2 much smaller than ocellus 1, ocelli 3 and 4 small, 

 adjacent and rudimentary, ocelli 5 and 6 wanting; antenna separated 

 from the mandible by a broad, chitinized area, second segment of the 

 antenna longer than all the other segments combined; maxilla with 

 the ventral sclerite of the cardo triangular and bearing eight or nine 

 setae; lacinia apparently absent; maxillary palpus three-segmented, 

 the proximal and second segments subequal in length and slightly 

 longer than the third, tlie proximal segment without a spine on the 

 latero-distal margin; labio-stipites heavily chitinized, concave, and 

 with a prominent carina on the lateral and caudal margins; ligula 

 chitinized on the ventral aspect, the chitinization of the ligula and 

 the labio-stipites extending around the palpiger; palpiger area 

 membranous and without a sclerite; labial palpus with the proximal 

 segment shorter than the distal segment and without spinelike pro- 

 jections on its ventro-distal margin, the proximal segment with 5 or 

 6 setae and the distal segment with 12 to 15; fifth abdominal seg- 

 ment with the inner and median hooks present, the lateral hooks 

 wanting, median hooks bluntl}^ thorn-shape, broad at the base, and 

 with 18 to 20 short, stout setae; inner hooks similar in shape to the 

 median hooks, about one-half their length, and with 12 to 15 short, 

 stout setae. 



