482 BRITISH FOSSIL REPTILES. 



fested in this character is considerable in the present order, although in no species has any 

 departure been observed from the predatory zoophagous condition. The teeth, always 

 simple and pointed, vary in shape, in nund^er, in position, in relative size. Pterodactylus 

 crassirosiris exemplifies the laniariform type of teeth, more or less elongate, and separated 

 by intervals of varying extent. In this not uncommon condition the teeth are longest in 

 the upper jaw, as offering more resistance than does the lower jaw in aid of the weapons 

 most deeply implanted in the struggling prey. 



In Pterodactylus lonyirostris the teeth are rather small, subequal, with short intervals, 

 a little widening toward the hind end of the series, which is restricted to the anterior half 

 of the jaw, both above and below. 



In some Pterosauria a certain extent of the fore part of both upper and under jaws is 

 edentulous, and from its shape has been inferred to have supported a horny sheath. The 

 teeth are long slender canines, with wide intervals. They number from about 8 to 10 

 on each side of the upper jaw, and from 7 to 8 in each ramus of the mandible. Von 

 Meyer proposed for this modification of mouth the generic name Rhamphorliyiiclius. 



Diinorphodon shows the combination of scattered laniaries, with small, more closely 

 set serial teeth in the lower jaw ; it has more numerous teeth, occupying a greater extent 

 of the alveolar margins of the jaws, than in any other Pterosaurian. 



The very small teeth which have been observed in tlie short jaws of the little Ptero- 

 dactylus brevirostris^ are most probably characters of inmiaturity, not of species. 



In regard to the bony structure of the head and the dentition, the general result of 

 observation and comparison of Pterosaurian fossils, and common consent of competent 

 investigators, having excluded the volant Mammals from the claim of affinity, the question 

 becomes narrowed to whether the skull in Pterosauria more resembles that in the cold- 

 blooded or the warm-blooded oviparous air-breathing Vertebrates. 



Hermann von Meyer, who has contributed a great and valuable share to our know- 

 ledge of the Pterosaurian order,^ quoting Oken's opinion, " that the skull is intermediate 

 in character between that of the Chameleon and Crocodile," sums up his own conclusions 

 on that head in the following terms :— " The skull oi Pterodactylus \?, essentially comparable 

 only with that of Birds and Saurians. The preponderating resemblance with the Bird's 

 skull cannot be contested. Against this, however, is a remarkable dissimilarity in certain 

 parts which, on the other hand, approximates it to the type of Saurians." ^ 



The term Sauria is here used in the sense of Brongniart and Cuvier, and it is open 



^ GoLDFUss, loc. cit., tab. .x, fig. 2. 



2 Especially in the admirable summarv of his own and others' researches, in the part of his great work, 

 'Zur Fauna der Vorwelt' relating to " Reptilien aus dem lithographischen Schiefer," &c,, fol., 1860. 



"* "Der Schadel der Pterodactyln, der uach Oken zwischen Chamaleon und Crocodil stehen wiirde, 

 lasst sich eigentlich nnr mit den Viigeln und den Sauriern vergleichen ; die iiberwiegende Aehnliehkeit mit 

 dem Vogelkopfe kann nicht bcstritten werden ; ihr gegeniiber steht aber eine auffallende Uniibnlichkeit in 

 gewissen Theilen, die dafiir ziim Zypus der Saurier hinneigen." — Op. cit., p. 15. 



