1873.] *■&* [Horn. 



The following genus presents so many characters at variance with our 

 genera of the tribe Hydrobilni that it seems necessary to place it by itself 

 as a distinct sub-tribe. From all Hydrophilidie known to me it differs in 

 having the genre at the sides broadly dilated and the labrum entirely con- 

 cealed beneath the clypeus in front. Excepting these two characters it 

 is a true Philhydrus, with the last joint of the tarsi more elongated 

 than usual. 



Helopeltis, n. g. 



Mentum transversely quadrate, slightly concave at middle, on each side 

 an oblique impression continuing on the sub-mentum where the two join. 



Maxillary palpi very long and slender, nearly as long as the head and 

 thorax, second joint one-fifth longer than the third, third and fourth 

 equal. 



Labial palpi short, not longer than half the terminal point of the max- 

 illary palpi, and with the terminal joint shorter than the preceding. 



Head broad, clypeus broadly rounded, genaj broadly dilated at the sides 

 and half dividing the eyes ; labrum concealed beneath clypeus. Middle 

 and hind tarsi with the first joint small, second equal to the two follow- 

 ing, which are very short, fifth as long as all the preceding together. 



Anterior tibial with outer edge not spinulose . 



Thorax and elytra broadly margined, margin extending beyond the 

 tip of the abdomen. 



H, larvalis, n. sp. 



Oblong, depressed, dark piceo-testaceous, opaque. Head opaque obso- 

 letely rugulose, in front piceo-testaceous, occiput piceous. Thorax nearly 

 three times as wide at base as long, sides moderately arcuate and feebly 

 narrowed anteriorly, apex emarginate, base at middle broadly but feebly 

 sinuous, surface opaque, obsoletely scabrous, smoother at the sides, mar- 

 gin slightly explanate. Scutellum elongate triangular. Elytra oblong, 

 sides feebly arcuate, margins broadly produced and somewhat explanate, 

 surface ten striate, the outer two indistinct, striae gradually obsolete 

 toward apex, punctulate, intervals flat, finely alutaceous and obsoletely 

 punctured, color piceo-testaceous, paler at the margins and irregularly 

 marked with small piceous spots. Body beneath piceous, opaque. Meso- 

 sternum and presternum simple. Femora piceous, opaque and pubes- 

 cent, apex smooth. Tibia* piceo-rufous. Length .22 inch ; 5.5 mm. 



The broadly produced margins of the thorax and elytra give this in- 

 sect a peculiar appearance recalling that of Peltis feruginea, as well as 

 of the larvse of some of our Elmidre. 



Two specimens are known to me, one from Louisiana in the cabinet of 

 Dr. Leconte, and one from Sonora in my own. A closely allied if not 

 identical species occurs in Cuba. 



A. p. s, — VOL. XIII. R 



