Classified tion . 1953 



order in many points of structure (very perceptible in the skull) to be 

 disregarded ; while the seals, which fortunately happened to possess 

 the posterior limbs, and a dentition somewhat resembling that usually 

 seen in the order to which they belong, were at an early period as- 

 signed to their true place among the Carnivora. As a well-known 

 example illustrative of what characters are really essential, although 

 their necessary connection with the plan of organization peculiar to 

 the type may not be very obvious, may be mentioned the articulation 

 of the head to the atlas by two condyles, one on each side of the oc- 

 cipital foramen ; the articulation of the lower jaw by a more or less 

 convex condyle, moving in a glenoid cavity excavated in the zy- 

 gomatic process of the temporal bone, instead of by a hollowed sur- 

 face in the jaw articulating with a condyle furnished to it by the 

 tympanic bone; the ossification of each ramus of the lower jaw from 

 one point, instead of its consisting, either originally or permanently, 

 of several pieces : these, among other peculiarities of greater or less 

 apparent consequence, are all so constantly associated in the Mam- 

 malian class with those before alluded to as being essential characters 

 of that group, that there can be no doubt of their appertaining equally 

 to the type, or model, upon which such animals are constructed ; and 

 a friend who has devoted some time to the examination of the minute 

 distribution of the sympathetic nerves about the face and within the 

 orbit of different animals, and who it is to be hoped may publish his 

 researches, recently informed the writer, that the Cetacea presented 

 in that respect precisely the same arrangement as in other Mammalia, 

 while in fishes it was widely different ; so that we need not always re- 

 ject a character because it is minute, if the course of observation 

 shows it to be constant in relation to the group in which we find it. 



It being here desirable to select such instances as, from their being 

 universally known and acknowledged, could not, most probably, with 

 reason be disputed, it will be seen that those mentioned refer exclu- 

 sively to the higher groups ; and as, even in these, errors are seen to 

 have crept into the systems adopted, through the masking of the es- 

 sential characters by the greater conspicuity of those relating solely 

 to the particular wants of the species, we may suppose, a fortiori, 

 since the differences between closely allied species consist merely of 

 adaptive variations and slight modifications of form, that, as we 

 descend from higher to lower groups, the essential distinctions be- 

 coming fewer and more difficult to perceive, there must be a far greater 

 scope for the labours of the systematist, in correcting the erroneous 

 principles on which the older classifications have been founded : and 

 the researches carried on within the last few years, by some of our 



