ZOOLOGY. 287 



dela and Anura] and Phractamphibia [=Laby- 

 rmthodonta + Gyrnnophiona]). 



Sub-grade C. Pentadactyla lipobranchia. 



Branch A. MoxocoxdyLuEA [=Sauropsida, Gill]. 



(9.) I. Reptilia (with sub-classes Ckelonia, Lepidosau- 

 ria, Pterosauria, Dicynodouta, Ornithoscelida, 

 and Crocodilia. 

 (10.) II. Aves. 



Branch B. AiipnicoxDYLA [=Malleifera, Gill]. 



(11.) I. Mammalia (with three grades, viz., Cloacalia 

 [ = Monotremata], Marsupialia, and Placentalia, 

 and with six sub -classes under Placentalia 

 viz., Edentata, Ungulata, Proboscidea, Chelo- 

 phora [=Hyracoidea], Carnaria [=Carnivora 

 -f-Pinnipedia+Cetacea] and Discoplacentalia). 



A few remarks as to the issues involved may be in place 

 here. 



It is safe now to affirm very positively that Branchiosto- 

 ma has been generally, until lately at least, associated alto- 

 gether too closely with the craniate Vertebrates, and that 

 there can be no doubt but what the hiatus between it and 

 the typical Vertebrates is greater than is that between any 

 other classes of the branch. The facts remain, however, 

 that morphologically Branchiostoma is by far more readily 

 comparable with the Marsipobranchiate Vertebrates than 

 with any other type, and that as to most of its peculiarities 

 of organization, it is not now difficult to appreciate the ho- 

 mologies with the several sj^stems in the latter: the denial 

 of the title of Branchiostoma to rank anions: the Verte- 

 brates because certain physiological functions are not car- 

 ried on as in the higher Vertebrates is a denial of the now 

 generally recognized dogma that physiology must not be 

 allowed to interfere with morphology in our appreciation of 

 the relations of living beings. We must admit that Bran- 

 chiostoma is not only not a fish, but quite remote from the 

 true fishes ; but it certainly seems to be more nearly related 

 to the Vertebrates than other animals, and, in fact, to be a 



