44 EXPLANATION OF PLATES 27". 27 b . 



Plate 27 a . V. I. p. 212. 



Fig. 1. Lepidosteus osseus, or bony Pike of North Ame- 

 rica. (Agassiz. Vol 2. Tab. A.) 



Fig. 2. Portion of the lower Jaw of Lipidosteus osseus, 

 showing the occurrence of a row of larger conical 

 hollow teeth, fluted externally, between two rows of 

 smaller Teeth. (Original.) 



2. a. Longitudinal section of a largo Tooth, showing the 

 internal hollow cone. (Original.) 



2. b. Transverse section of a large Tooth. (Original.) 



Fig. 3. Transverse section of the Jaw. fig. 2. (Original.) 



Fig. 4. Fragment of a small upper Jaw of Megalichthys 

 Hibberti, from Burdie house, showing a disposition 

 of large and small teeth, similar to that in fig. 2. 

 (Hibbert.) 



4. a. b. Transverse section of the larger teeth. 



4. c. Longitudinal section of a large Tooth.* 



4. d. Punctate scale of Megalichthys. 



Fig. 5. Aspidohrynchus : a fossil Sauroid fish from the 

 Limestone of Solenhofen. (Agassiz, Vol I. Tab. F.) 



Plate 27 b . V. I. p. 212. 



Amblypterus : one of the fossil fishes peculiar to the Car- 

 boniferous strata. Agassiz, Vol. I. Tab. A. fig. 3.) 



* It appears that in the Megalichthys and Holoptychus the struc- 

 ture of the teeth, both large and small, was precisely the same as in 

 the large and small teeth of Lepidosteus osseus, both as to the hollow 

 internal conical cavity, and the external flutings towards the base, and 

 also as to their mode of growth by ascent of fibrous matter from the 

 bony substance of the jaw, and not from roots placed in deep alveoli, as 

 in many of the Saurians. 



