262 
ME. CHAELES S. TOMES ON THE 
Teleostei . — Sections of the jaws of the Perch, Pike, Eel, Haddock, Cod, Mackerel, and 
Trout have been examined, and have been found to agree so closely in most points, that 
it is possible to embody the leading features of the process in a general description. 
The literature of the subject may be disposed of in a very few words ; in the first 
place, there is the view held by Professor Owen, and concisely expressed by him as 
follows : — “ In all fishes the first step is the simple production of a soft vascular papilla 
from the free surface of the buccal membrane;” and “ In many fishes, e. g. Lo'pliius , 
JEsox , the dental papillae become buried in the membrane from which they rise, and the 
surface to which their basis is attached becomes the bottom of a closed sac and again, 
“ Here, therefore, is represented the 4 follicular’ stage of the development of a mammalian 
tooth ; but the ‘ eruptive ’ stage takes place without previous inclosure of the follicle and 
matrix in the substance of the jawbone.” (Anatomy of Vertebrates, vol. i. p. 382.) 
A much more accurate account of the process as it occurs in the mackerel is em- 
bodied in Professor Huxley’s paper, already several times alluded to ; the fact that the 
papilla is never free and that it is surmounted by an enamel-organ derived from and 
continuous with the oral epithelium is clearly laid down ; and Kolliker mentions that 
the teeth of all osseous fish are developed^ in sacs not altogether from free papillse. 
Nevertheless the exact nature of the process has not, so far as I know, been described 
by any previous author. 
In all cases the whole series of changes take place beneath an unbroken surface, and 
often at some little depth ; in this respect, however, differences are met with upon 
different bones in the mouth of the same fish, so that this would appear to be influenced 
by accidents of situation. 
From the deepest layer of the oral epithelium, which is very thick in many fish, 
there dips downwards a blunt-ended process, descending into the loose connective tissue 
beneath. When it approaches the surface of the bone, a dentine-pulp is developed in 
the subjacent connective tissue, which it eventually covers over like a cap or bell-jar. 
The epithelial process, making its way downwards, is recognizable before the dentine- 
papilla can be distinguished ; its end becomes transformed into an enamel-organ, but no 
very definite capsule is formed around the dental germ. 
There is therefore no “papillary” stage and no “follicular” stage, in the sense in 
which these terms are ordinarily used ; the only appearance at all suggestive of the 
existence of free papillae with which I am familiar is to be met with in the haddock, in 
which fish the tissues above a forming tooth-germ become elevated in places into a 
sort of papilla, which is, however, altogether external to and distinct from any part of 
the dental germ, which latter constitutes less than one third of its bulk and is far 
below its surface. 
more minuteness than I have done. But I do not think that the grounds which he has adduced for asserting 
the existence of a memhrana preformativa in the sharks are adequate to weigh against the reasons which have 
led "Wai/deter and others to doubt its existence ; and my own researches in this direction lead me to the belief, 
long ago expressed by my father, that the appearances described are susceptible of a different interpretation. 
