{ 4. ὄρνιθες. Birds. { (a) γαμψώνυχα. Birds of prey with { talons. { (b) στεγανόποδες. Swimmers with { With { webbed feet. { perfect { (c) περιστεροειδῆ. Pigeons, doves, &c. { ovum. { (d) ἄποδες. Swifts, martins, &c. { { (e) ὄρνιθες ἕτεροι. Other birds. Oviparous { { 5. ζὌῷα τετράποδα ῷοτόκα. Oviparous though { { quadrupeds = Amphibians and most sometimes { { reptiles. _externally_ { { 6. ὀφιώδη. Serpents. viviparous. { { { 7. ἰχθύες. Fishes. { With { (a) σελάχη. Selachians. Cartilaginous { imperfect { fishes and, doubtfully, the { { fishing-frog. { ovum. { (b) ιχθύες ἕτεροι. Other fishes. _ANAIMA_ (_Non-sanguineous and either viviparous, vermiparous or budding_) = _Invertebrates_. With perfect ovum. { 8. μαλάκια. Cephalopods. { 9. μαλακόστρακα. Crustaceans. With ‘scolex’. 10. ἔντομα. Insects, spiders, scorpions, &c. With generative }11. ὀστρακόδερμα. Molluscs (except slime, buds or } Cephalopods), Echinoderms, &c. spontaneous generation. } With spontaneous }12. ζωόφυτα. Sponges, Coelenterates, generation only. } &c. Some of the elements in this classification are fundamentally unsatisfactory in that they are based on negative characters. Such is the group of _Anaima_ which is parallelled by our own equally convenient and negative though morphologically meaningless equivalent _Invertebrata_. Others, such as the subdivisions of the viviparous quadrupeds, can only be forcibly extracted out of Aristotle’s text. But there are yet others, such as the separation of the cartilaginous from the bony fishes, that exhibit true genius and betray a knowledge that can only have been reached by careful investigation. Remarkably brilliant too is his treatment of Molluscs. There can be no doubt that he dissected the bodies and carefully watched the habits of octopuses and squids, _Malacia_ as he calls them. He separates them too far from the other Molluscs, grouped by him as _Ostracoderma_, but his actual descriptions of the structure and sexual process of the cephalopods are exceedingly remarkable, and after being long disregarded or misunderstood were verified and repeated in the course of the nineteenth century.[54]