. Coleoptera. Beetles. Fig. 463. — UudroiihUus shining black species, tuund in the northeastern United Slates. The form is nearly hemispherical, the length from to of an inch. The genus JL/drophihis contains the largest species of this family. They differ from Hijdrobiaii and genera associated with it in having compressed tarsi, and in hav- ing the metasternuni prolonged posteriorly into a long sjiine. H. trktuguluris, a common North American species, is inches long, and shining black in color. The egg-case of this species has been carefully described by Dr. C. V. Ri
. Coleoptera. Beetles. Fig. 463. — UudroiihUus shining black species, tuund in the northeastern United Slates. The form is nearly hemispherical, the length from to of an inch. The genus JL/drophihis contains the largest species of this family. They differ from Hijdrobiaii and genera associated with it in having compressed tarsi, and in hav- ing the metasternuni prolonged posteriorly into a long sjiine. H. trktuguluris, a common North American species, is inches long, and shining black in color. The egg-case of this species has been carefully described by Dr. C. V. Riley. It consists of three parts, a floater surmounted by a horn-shaped process, au egg-case projjer, attached to the basal end of the floater, and an outer bag or covering. The larvae remain a day or two in the outer bag after they hatch ; and Dr. Riley concludes " that the curious contrivance in JL/drophilKs is intended not only to secure an anijile supjily of air to tlie eggs and to protect them, but also to ]irotect the newly hatclied young from their nu- merous enemies until their jaws have strengthened and they are better able to begin the struggle for ; The eggs are white, cylindroid, and aViout of an inch long and .04 of an inch in diameter. In Euro|ie the corresponding large s]iecies of this genus is II. iiircas, both of which are figured above, with nest and larva. The sexes of these insects are easily dis- tinguished, because the male has the anterior tarsi much en- lai'ged, to form an organ, common among water beetles, by which he clings firmly to the female during copulation. Notwithstanding the rejjuted phyto- phagous habits of the imago of H. jiictus, this beetle sometimes captures and eats Tri- t07ipunctatus, when confined in an aquarium. Nearly related to Ili^/drophilus, but having a short metasternal spine, is Hydro- charis. II. obtasatus, an oval black sj)ecies, about of an inch long, is common in the eastern United
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Keywords: ., boo, bookcollectionbiodiversity, booksubjectbeetles, bookyear1884
