As further instances of mutations among animals which have been observed in nature, we may mention the _valezina_ form of the female of the Silver-washed Fritillary Butterfly (_Argynnis paphia_) and the _helice_ form of the female Clouded-yellow Butterfly (_Colias edusa_). The common jelly-fish is an organism which frequently throws off sports, and some zoologists are of opinion that the medusoid _Pseudoclytia pentata_ arose by a discontinuous variation from _Epenthesis folleata_ or a closely allied form. Thomson discusses this particular case at some length on pages 87-89 of his _Heredity_, and gives it as his opinion that the evidence in favour of this latter having arisen as a mutation is “exceedingly strong.” Mutating Species It is our belief that many species of birds which occur in nature have been derived from other species which still exist, but as no one has ever seen the mutation take place, we cannot furnish any proof thereof. We merely rely on the fact that the species in question differ so slightly from one another that there seems every likelihood that they have suddenly arisen and managed to establish themselves alongside of the parent species. The Curassows, _Crax grayi_, _C. hecki_, each of which is only known by a very few specimens, appear to be mutations of the female of the globose Curassow, _Crax globicera_. The fact that when a female _hecki_ bred in the London Zoological Gardens with a male _globicera_, the solitary young one which lived to grow up was a pure _globicera_, renders the assumption almost certain. The Chamba Monaul (_Lophophorus chambanus_) seems to be a mutation of the male of the common Monaul or Impeyan Pheasant (_Lophophorus impeyanus_), the common species of the Himalayas. The Three-coloured Mannikin (_Munia malacca_) of South India is probably simply a white-bellied form of the widely-ranging Black-headed Mannikin (_M. atricapilla_), which has the abdomen chestnut like the back. Intermediate wild-caught forms have been recorded. The African Cordon-bleu (_Estrelda phœnicotis_) and Blue-bellied Waxbill (_E. cyanogastra_) would also seem to be mutations, as almost the only difference between them lies in the fact that the male of the former has a crimson cheek-patch, which is wanting in the latter. The Ringed Finch (_Stictoptera annulosa_) of Java, and Bicheno’s Finch (_S. bichenovii_) of Australia, only differ in the former having the rump black, while in the latter it is white, and this difference appears to be of the nature of a mutation. So, it might be urged, is the pure white breast of the male Upland Goose (_Chloëphaga magellanica_), which part, in the very similar _C. dispar_, is barred as in the females, the latter form being probably the ancestor.