OCR Text |
Show 480 PROF. G. GULLIVER ON [Jlllie 1 5, Osmerus, in which the corpuscles are much smaller than in certain Apodes. The smallest corpuscles occur in some of the little species of Acanthopteri and Anacanthini, and in the Sprat and Herring, while their congener the Pilchard has slightly larger corpuscles. They are somewhat larger in the river-Eels than in the Conger. In no single order of fishes are the corpuscles twice as large in one species as in another; they are quite as large in the osseous Salmon as in the cartilaginous Sturgeon, and in the Sharks and Rays so much larger as to adumbrate a distinct class. Lepidosiren has the corpuscles of such still greater magnitude as to depart in this respect from any regular fish to reach the saurobatrachian character. BATRACHIANS. Form and size of the corpuscles.-On each broad surface they are generally fiat or somewhat vaulted; and their outline is regularly a well-defined oval figure, mixed occasionally with a few of a suboval or even circular shape, as indeed is the case among all regularly elliptical blood-disks, though this is rarer in Birds than in the lower classes and in the Camels. In Batrachians, the short diameter of the corpuscle being taken as 1, its long diameter -would vary commonly between 1^ and 1|. The thickness of the corpuscle is about one third of its short diameter ; and the nucleus may be either sub-rotund, or more commonly liker in shape to the envelope. The largest red blood-corpuscles of Vertebrates occur in the tailed Batrachians, of which Amphiuma, a cauducibranchiate species, has the largest of all, so that these are visible to the naked eye, and the perennibranchiate Proteus the next in size; and in Sieboldia, which has deciduous gills, the corpuscles are larger than in Siredon, which has permanent gills. In Amphiuma and Proteus the corpuscles are at least thrice as large as in some Frogs and Toads-an amount of difference of which there is no example either in the class of Birds or Reptiles, though it is exceeded among Apyrensemata. The corpuscles in the anurous Batrachians are not always bigger than, and sometimes not so long as, in a few reptiles and in some Sharks and Rays. The size of the corpuscles in Batrachians may differ in the same individual at different seasons. A few more observations on the corpuscles in this class are given in the ' Proceedings of the Zoological Society,' Feb. 4, 1873. REPTILES. Form and size of the corpuscles.-They are oval, flattish, little tumid on each broad surface-much of the same shape as, but generally rather longer in proportion to their breadth than, in Batrachians, as is the case, too, in some birds. And as in such elongated shape of the corpuscles in a few species (e.g. Anguisfragilis and Crocodilus lucius, Syrnea nyctea and Columba migratoria) Reptiles and Birds agree, so they differ from the other classes. Of Reptiles the largest corpuscles occur in some Crocodiles and Tortoises, and the smallest in the little Saurians and larger Teius and Monitor ; the reptilian corpuscles are smaller than those of the batrachian Urodela, but in |