34 
IT. 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 elongato, 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, canaliculato, antrorsum angustato 
lateribus suberratis, ad medium subangulatis, postice subangustato, angulis posticis acutis elytris 
ovalibus, substriatis, scabro-punctatis, thorace duplo latioribus. Long. 52°. Tab. —, fig. 11. 
Lee. Proc. Acad. Nat. Sc. 6, 288. 
Sacramento ? California; collected by J. Child, esq, and given me by Mr. S. S. Rathvon. 
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 difference was observed between five specimens. 
Agabus Leach. 
A. brevicollis, obtuse ovalis minus convexus, totus niger vix aenescens, (mas alutaceus, femina 
subtiliter reticulata,) thorace latitudine triplo breviore antrorsum valde angustato, lateribus late 
rotundatis cum elytris angulum haud 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. 
Acilius Leach. 
A. latiusculus, ovalis minus convexus, supra piceo flavoque irroratus, capite thoraceque 
maculis solitis flavis, elytris (feminse) punctulatis, limbo fasciaque postica irregulari flavis, 
sulcis utrinque quatuor exaratis, primo breviore, alterisque ad basin haud 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.fra- 
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 Lee., found in southern 
California. A. abbreviatus 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. sublimbatus, elongato-ovalis, postice vix latior, supra nigro-piceus, thorace latitudine 
triplo breviore, lateribus subrotundatis late testaceis, linea angusta subapicali alteraque minus 
