Monograph on Dimorphodon. 135 
those of birds and lizards; but the foramen is missing from it 
Which perforates the hinder half of the lower jaw in birds and 
in crocodiles. With all this resemblance, it is amazing to see 
the Jaws armed with teeth, which are planted in separate 
alveoli, like those of crocodiles, and which have the succes- 
sional tooth at the side of the old one, as in lizards. The 
mechanism of the hyoid bone is more bird- and reptile-like.” 
figured the premaxillary bone of Pterodactylus compressirostris 
(Owen), which extended back to the nasal cavity, and demon- 
strated that the teeth were in the premaxillary bone. Ac- 
cordingly Prof. Owen made a restoration of the Lan. in which 
the premaxillary and maxillary bones have avian proportions. 
But in Dimorphodon it is said of the premaxillary, “ The pair, 
by confluence or connation, constitute the fore part of the 
upper jaw ” (p. 58), And in the description of plate 17 it is 
said, * Beyond the fourth alveolus the maxillary (20) appears, 
underlapping the part of the premaxillary (22") which defines 
tered to agree with the description ; but D = "E - 
y founded) is let- 
said, * In no Pterosaurian has any obvious and unmistakable 
suture been seen indicative of the respective shares taken by 
maxillary (21) and premaxillary (22) in the formation of the 
dentigerous part of the upper jaw,” &c. 80, it is not evi- 
dent why Prof. Owen asserted, but a few pages before, that 
there was a suture, and described the extent and character of 
the alveolar rays of the premaxillary bone. we are to be- 
lieve this last statement, then it is evident that both views 
given in the plates are incorrect, and that every passage in 
