NATURAL SCIENCES OF PHILADELPHIA. 19 MATERIALS FOE THE STUDY OF THE PHYTOPHAGA OF THE UNITED STATES. BY G. R. CROTCH, M. A. CANTAB. The following paper does not profess to bean exhaustive raono-grapli upon this group; for such a work the tiine is not come, and the species here noticed will be nearl\^ doubled if they are dili-gently collected and observed in diiterent States. In particular, I would call attention to the HaUicini, as being in almost a com-plete chaos. I have endeavored to diagnose the various genera, adding as few as possible at present, and to give tables, and often diagnoses of all the species ; in some intricate genera, I have, however, abstained from remark. The immediate object of this publication is to make known the numerous unnamed species common in collections, in order that they may be inserted in the forthcoming check list of the Coleoptera of the United States, now ],rinting at Salem. All the species described are from the cabinets of Drs. Leconte and Horn, without whose help and aid, this paper could not have been attempted. CHRYSOMELIDiE. Form elongate, thorax not margined, head constricted behind. Ist ventral segment very long, claws sunple. Bonaciides. 1st ventral segment not longer than the rest. Claw^s dentate, posterior coxae nearly contiguous. Orsodacnides. Claws simple, connate. Criocerides. Form more or less rounded, thorax margined, head inserted. Antenna? distant. Pygidium vertical, bare, Itist ventral segments connate. Anterior coxae prominent, contiguous. 3felolont7iides. Anterior coxae transverse, distant. Cryptocephalides. Abdomen normal. Anterior coxa? transverse, claws generally simple. Chrysomelides. ^ Anterior coxae globose, claws bifid. Eumolpides. Antenna; approximate, anterior coxa conical, prominent. Oalerucides. Form variable, antennae approximate, inserted on the front. Head free, form elongate. liispides. Head hidden under the thorax, elytra explanate. Cassidides.