TBANSACTIONS OF SECTION D. 689 



Hunter, Meckel, Owen, and others have mentioned the occurrence of these extra- 

 numerary teeth. Wedl (' Pathologic der Zahne ') gives a good description of them, 

 stating that wliilst six incisors are very rare, five ai-e of more common occurrence, 

 the additional tooth, when of the supplemental group, being generally a lateral 

 incisor. "When supernumerary they are placed either amongst the permanent teeth 

 or behind them within the alveolar arch. Their eruption takes place during the 

 first or second dentition, or in the interval between the two ; generally, however, 

 they belong to the permanent series. Baume (' Odontologische Forschungen ') states 

 his belief that the archaic incisor dentition of man was In J}, and that the missing 

 teeth are the median lUj in each case. This theory he bases upon the facts (1) 

 that a separation may exist between the median incisors in man and the higher 

 apes^ and (2) that in this position superfluous teeth may exist. Dr. Edwards, of 

 Madrid, shares his opinion for somewhat similar reasons. Professor Turner, from 

 a study of a number of cases of alevolar cleft palate, believes the missing incisor to 

 be the second, that is, In„. This view is shared hj Albrecht and Andrew Wilson. 



The specimens upon which we base this communication may be arranged in 

 eight groups. We have obtained most of the casts ourselves at the Birmingham 

 Dental Hospital. Others we owe to the kindness of Messrs. Sims and Adams 

 Parker, of this town ; Dr. Crapper, of Hanley ; Mr. Percy May, of London ; and 

 Mr. J. S. Amoore, of Edinburgh. 



The groups which we describe are as foUows : — 



(Series i.) Su])plemental teeth. — In this group we have one case of six separate 

 incisors (sup. max.), and one of six, the two central being geminous, and seven 

 in which there were five teeth. Of these seven three were on the right, four on the 

 left side. In all the cases save one they were situated behind the true lateral, 

 generally occasioning some displacement. In one case, however, the intruder was 

 placed between the lateral and central. One case only belonged to the milk denti- 

 tion, and all but one were found in the upper jaw. 



(Series ii.) Svjjernumerary teeth. — We have four casts in which there are two of 

 these teeth : in two they were situated behind the median incisors ; in another one 

 was posterior to the left lateral, and a second between the right median and lateral ; 

 and in the fourth one was posterior to the right central, and the second between 

 the two median. In fifteen cases there was one supernumerary. These teeth were 

 situated inside the alveolar arch posterior to the left median incisor in seven cases, 

 the right in five, and in the middle line in three instances. They generally caused 

 more or less displacement of the remaining teeth. All were found in the superior 

 maxilla, and all belonged to the permanent series. 



(Series iii.) Coexistence of suppletnenf.al and supernumerary with the normal 

 number of incisors. — Of this we have one specimen, in which a properly formed 

 though small incisor is placed behind the right lateral, and in series with it, and a 

 blunt tooth posterior to the left median, which it displaces forward. This was in 

 superior maxilla and permanent series. 



(Series iv.) Substitution of a siipernumerary tooth for a nonnal incisor, the 

 nu7nber of teeth remaining four. — Of this we have four specimens. The substitu- 

 tion was once each for the right and left median, and twice for the left lateral. 

 All the cases belonged to the superior maxilla and to the permanent series. 



(Series v.) Substitution of tico superyvumerary teeth for normal incisors, the 

 number of teeth remaining four. — Of this we have six cases, the two lateral superior 

 incisors of the permanent series being those always to suffer. 



(Series vi.) Absence of one incisor, the number being three. — In two cases the 

 right lateral (superior) incisor was wanting, and in one the same tooth in the in- 

 ferior maxilla. All three were of the permanent series. 



(Series vii.) Absence of one incisor, diminution or malformation of another, the 

 number being three.— Oi this we have three cases. In two the right lateral was 

 absent. The left lateral was conical in one of these, small but incisiform in the 

 other. In the third case the left lateral was absent and the right lateral small 

 though incisiform. All were of the superior maxilla and permanent series. 



(Series viii.) Absence of tivo incisors, the number being reduced to two. — Of this 

 we have seven cases, all belonging to the superior maxilla and pfrmanen*^. series. 



1886. T T 



