84 SCLERODERMS. 



posed in their alveoli in the left intermaxillary bone, are figured in 

 Plate 40, fig. 6. 



The number of the teeth is not constant in the genus Batistes, but 

 in no species examined by me were the posterior teeth of the upper 

 jaw absent. In an Australian species, I found six teeth in the outer 

 row and four in the inner row of teeth in the upper jaw. The apices 

 of the mesial pair of the posterior row projected between those of the 

 first and second teeth of the outer row. 



In all the file-fishes, the pharyngeal teeth are small, conical, laterally 

 compressed, curved and sharp-pointed ; regularly arranged in two 

 rows upon the opposed margins of each of the two upper and lower 

 pharyngeal bones. A view of the upper and lower left pharyngeal 

 bones, in situ, is given in figure 2, Plate 40. The direction of the 

 curvature and the relative size of the anterior and posterior teeth are 

 reversed in the two bones, which thus form an admirable carding 

 machine for "teazing" the bruised and coarsely divided sea-weeds 

 or other marine nutrient substances w^hich the fish has obtained by 

 means of its large maxillary teeth. 



Microscopical sections of these dense teeth in the Batistes forcipatus 

 present a structure so closely corresponding with that described by 

 Professor Retzius in the Batistes Vetula, that a better idea of it can- 

 not be conveyed than in the words of that excellent observer. He 

 says,(l) "That the dentine (zahnknoche) of both the Balistes and 

 Sparus resembles most in internal structure that of the teeth of mam- 

 malia and reptiles, being white and hard, like ivory, and displaying 

 under the microscope beautiful, regular, minute and parallel tubes. 

 These, in Balistes vetuta, are j^^ of a Paris line (2) in diameter, and are 

 beautifully parallel, save in their last formed parts at the coronal end 

 of the pulp-cavity. Their undulations are long and slight. Their 

 interspaces are equal to their own diameter. The larger branches lie 

 close to the trunks, while the smaller ones generally bend away in a 



(1) Miiller's Archiv. 1837, p. 323. 



(2) The French inch of twelve lines is so nearly one-fifteenth more than the Enghsh inch, 

 that the conversion of the fraction of a French line into the fraction of an English inch by mul- 

 tiplying the denominator of the former by 1 li, is sufficiently accurate for all practical physio- 

 logical purposes ; thus the calcigerous tube measuring i-oWth of a Paris line, will be xTwuth of 

 an English inch. 



