Mr. W. C. Hewitson on some new species of Butterflies. 257 The young state of this species and for a considerable period of growth scarcely presents any trace of the sinuated margin. This shell, which cannot be separated from Ter. maxillata, Sow., has lately been found of large dimensions ; we have speci-mens attaining more than two inches in length and the same in breadth ; thus it would appear that under favourable conditions this species attained a much larger size than that figured by Mr. Sowerby before it exhibited the strongly sinuous front. In reference to this shell Mr. Walton states, that it is the same as Ter. maxillata, and this assurance is founded on that expe-rience which is attained by the examination of thousands of spe-cimens. This Terebratula varies much in size and form, its greatest diameter being sometimes in the longitudinal and some-times in the transverse direction of the shell. Some varieties are deeply plicated, others have no plicse at all ; it is found quite small at Hampton Cliff and very large at Pickwick, and is dis-tributed plentifully through the forest marble, Bradford clay and great oolite around Bath; it is also abundant near Sapperton and Hailey Wood. XXIV. — Descriptions of new species of Butterflies. By William C. Hewitson. [With two Plates.] Family NYMPHALID^E. Genus Heterochroa, Boisduval. The genus Heterochroa of Boisduval is remarkable amongst butterflies for the close affinity which its species bear to one another, and yet also for the great beauty and variety of design which it presents and with colours so simple and so few. The twelve species which I have figured, most of them new and all hitherto undescribed, are but half of the genus. They are all inhabitants of the New World. Some of them, H. Nea, Melona, Erotia and Lerna, are much more robust than the rest. H. Fessonia and Cestus, besides the unbroken and conspicuous band of white, have other characters peculiar to themselves. The cell is shorter and the disco-cellular meets the median nervure somewhat nearer to the body. The outlines on the plates show portions of the underside of the wings characteristic of each species. Heterochroa Nea. PI. XX. fig. 1. Wings dark brown with a central band common to both, com-mencing at the third median nervule of the upper wing, and ex-tending to the anal angle of the lower, on the upper wing broad
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