228 [ JANUARY, 
a ho 
or ambulatorial type. The posterior coxe also differ greatly in the two fami- 
lies, those of Haliplus being dilated into a broad plate, under which the poste- 
rior legs can be withdrawn. We must, therefore, conclude that the differences 
between Amphizoa and the two families just mentioned, are not of greater 
value than the differences between those two families themselves. 
The other relations of this insect from the form of the tarsi, would appear to 
be slightly towards Parnus. The roughness of the surface above and below is 
of a peculiar nature, and resembles very much what is found in certain Bupres- 
tide ; in fact, from the general appearance of the insect, it would at first sight 
be supposed to have some affinity to the broad Madagascar Buprestide forming 
the genus Polybothris. Of its habits nothing is known. 
I would therefore divide the group now under consideration into four families, 
thus: 
A. Mesosternum parvum; (antenne filiformes, oculi duo, coxe intermediz 
globosa.) 
1. Pedes ambulatorii, tenues, coxe postice transverse, mediocres. AMPHIZOIDR. 
2. Pedes subnatatorii, tenues, coxe postice magne laminate. HaLipLipm®. 
3. Pedes postici natatorii, compressi, coxe postice magne, sim- 
plices. Dytiscipm. 
B. Mesosternum maximum ; (antenne breves, perfoliata, oculi quatuor.) 
4, Pedes posteriores natatorii, valde compressi, coxa intermedi 
triangulares plane. GyRINIDE. 
Having now ascertained as far as practicable the position of Amphizoa, we 
may proceed to the specific description of the only species yet obtained. 
A.insolens, atra, opaca, subvirescens, glabra, thorace scabro, canalicu- 
lato, antrorsum angustato, lateribus subserratis, ad medium subangulatis, 
postice subangustato, angulis posticis acutis, elytris ovalibus, substriatis, 
scabro-punctatis, thorace duplo latioribus. Long. -52. 
Sacramento, California, collected by Mr. J. Childs, and given me by Mr. 
Rathvon. Color dull black, slightly tinged with greenish, without lustre. Head 
irregularly rugous and punctulate, with two shallow impressions between the 
antenne. Labrum covering the obtuse mandibles, slightly and broadly emar- 
ginate in front. Thorax twice as wide as the head, flat, scabrous; sides sub- 
serrate, strongly narrowed from the middle to the apex, slightly narrowed and 
subsinuate posteriorly ; base very broadly bisinuate, posterior angles acute; 
disc channeled, 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 
observed in five specimens examined. 
Srenocouus Lec. (Atopide.) 
Tarsi elongati tenues, unguibus simplicibus, paranychio bisetoso; caput 
clypeo distincto, antice membranaceo; mandibule apice integre; antenne 
elongate, serrate, articulo 2ndo minuto ; palpi maxillares breviusculi cylindrici. 
This genus resembles in its characters Anchytarsus Guériz, but differs in 
having a distinct transverse suture each side between the antenne; in the 
middle this suture is not obvious, but the front is slightly elevated, so that the 
suture appears slightly sinuous; the anterior part of the clypeus is membra- 
neous; the labrum is transverse and rounded; the eyes are round, the proster- 
num projects posteriorly, and the mesosternum is concave; the tarsi are long 
and slender, the first four joints are very slightly pubescent beneath, and 
the first joint is a little elongated; the last joint is as long as the three pre- 
ceding united. The claws are moderate and simple; the intermediate appen- 
dage is small and terminates in two bristles. 
