other, have no ambiens; but from their general resemblance in other particulars to birds which have an ambiens, it was thought by Professor Garrod that the loss in them was a recent event, and that they might be fairly placed in one great group of birds with an ambiens which he termed, somewhat lengthily, the ‘homalogonatæ,’ or normal-kneed birds, reserving the name ‘anomalogonatæ,’ or abnormal-kneed birds, for the passerines, &c., without an ambiens. _CLASSIFICATION_. One great advantage of the study of birds is that the amount of facts to be learnt in anatomy is far less than with some other groups. They are wonderfully uniform in structure. There is less difference in structure between an ostrich and a humming-bird than between, say, a lizard and a crocodile. Though this may be gratifying to the student of birds who is content with a broad knowledge of anatomical fact, it has its disadvantages--very distinct disadvantages--to those who want to arrange and classify the species. As there are computed to be over eleven thousand different kinds of birds, it is clear that an arrangement of some kind is wanted; we must have an artificial brain in which to store the characters of each bird in their proper place. But before we can consider this it is necessary to consider first what place birds as a whole occupy in Nature. It used to be thought that warm-blooded birds ought to be put near to the warm-blooded mammals. But it is now the general opinion that, as we have before pointed out in relation to certain details of structure, their proper place is in the neighbourhood of the reptiles. In fact they are regarded as a separate division of an order of vertebrated animals which has received the name of Sauropsida, which signifies ‘lizard-like’ animals.