34 U. S. p. R. R. EXP. AND SURVEYS — ZOOLOGY — 47TH PARALLEL. 



cylindricis ; prosternum postice productum rotundatum, mesosternum antice carinatum declive, 

 postice late excavatum ; tarsi articulo ultimo elongate, subtus ad apicem utrinque emarginato, 

 et medio rotundatim producto (sicut in Carabis,) postici articulo primo secundo sesqui longiore, 

 omnibus subtus convexis, pubescentibus baud setosis ; unguiculi simplices. 



A. insolens, atra, opaca, subvirescens, glabra, tborace scabro, canaliculate, antrorsum angustato 

 lateribus suberratis, ad medium subangulatis, postice subangustato, angulis posticis acutis elytris 

 ovalibus, substriatis, scabro-punctatis, tborace duplo latioribus. Long. 52°. Tab. — , fig. 11. 



Lee. Proc. Acad. Nat. So. 6, 288. 



Sacramento ? California ; collected by J. Child, esq, and given me by Mr. S. S. Katbvon. 

 Color dull black, tinged with greenish, without lustre. Head irregularly rugous and punctulate, 

 ■with two shallow impressions between the antennae. Labrum covering the obtuse mandibles, 

 slightly and broadly biemarginate in front. Thorax twice as wide as the head, flat, scabrous, 

 sides subserrate, strongly narrowed from the middle to the apex, slightly narrowed and subsinuate 

 behind ; base very broadly bisinuate, posterior angles acute ; disc channelled, with a shallow 

 impression each side at the base, and a broad transverse one before the middle. Elytra broadly 

 oval, slightly convex, nearly twice as wide as the thorax, scarcely one half longer than wide, 

 scabrous with shallow punctures, striate with nine slightly impressed grooves, which appear 

 coarsely and indistinctly punctured. Scutellum flat, broad, acute at apex. Under surface of the 

 body covered with shallow confluent punctures and wrinkles. Legs scabrous with fine elevated 

 punctures. No sexual dlflerence was observed between five specimens. 



Agabus Leach. 



A. hrevicollis, obtuse ovalis minus convexus, totus niger vix aenescens, (mas alutaceus, femina 

 subtiliter reticulata,) tborace latitudine triple breviore antrorsum valde angustato, lateribus late 

 rotundatis cum elytris angulum baud formantibus, his seriebus solitis punctorum minus dis- 

 tinctis. Long. '35 — '44. 



Upper Sacramento river ; Mr. Child. Resembles in form A. stagninus, but is very different 



in its color and other characters. The punctures of the elytra are less numerous than usual, 



and the rows become indistinct towards the tip — not by being confused, but from the roughness 



of the surface. 



AciLros Leach. 



A. latiusculus, ovalis minus convexus, supra piceo flavoque irroratus, capite thoraceque 

 maculis solitis flavis, elytris (feminas) punctulatis, limbo fasciaque postica irregulari flavis, 

 sulcis utrinque quatuor exaratis, primo breviore, alterisque ad basin baud extensis, subtus 

 cum pedibus testaceis, suturis fuscis. Long. '52 ; lat. 'SI. 



One specimen from the Upper Sacramento ; Mr. Child. This species is broader than A./ra- 

 ternus, and the outer furrows of the elytra are a little longer ; the pale color of the under 

 surface will at once distinguish it from that species, and from A. simplex Tiec, found in southern 

 California. A. abhreviatus Mann., which was found by Dr. Cooper at Fort Vancouver, is testa- 

 ceous beneath, but the form of body is still narrower than in A.fraternus. 



Dytiscus Linn. 



D. suhUmbatus, elongato-ovalis, postice vix latior, supra nigro-piceus, tborace latitudine 

 triplo breviore, lateribus subrotundatis late testaceis, linea angusta subapicali alteraque minus 



