LABYRINTHODONTS. 205 



the centres of minor ramifications, defies all calculation. Their diameter 

 is yi^h line, with interspaces equal to seven diameters of their cavi- 

 ties. Their general disposition is shown in a section of one of the simple 

 lateral processes of the radiating plates of dentine (PI. 64 a, fig. 2). 

 The undulation and ramification of the extremities of two of the calci- 

 gerous tubes, magnified 650 diameters are figured at PL 64 a, fig. 3. 



It has already been stated that among the few teeth, presumed to 

 be saurian, from the lower Warwick sandstone, the small conical exter- 

 nally striated one, figured in Plate 62 a, fig. 2, bears the nearest 

 resemblance to the teeth of the German Labyrinthodon; it is, however, 

 much smaller, and the cone is broader and shorter, and the base of the 

 tooth is more ventricose. 



I subsequently received a larger tooth from Dr. Lloyd, which was 

 discovered in the Warwick sandstone at the Coten-end quarry. This 

 tooth (PI. 64 B, fig. 1) presented a more simple and regular conical 

 shape, and differed from the tusk of the great Labyrinthodon Jaegeri in 

 being somewhat more compressed at the base, and less obtuse at the 

 apex. Its external surface was similarly impressed with fine longitudinal 

 striae continued, with a very slight degree of convergence, towards the 

 apex of the tooth, where the longest strise terminated. The interspaces 

 of the strice were more prominent and convex than in the tooth of the 

 Lah. Jaegeri. The apex of the tooth, though obtuse, was worn 

 by attrition obliquely down one side, and did not present the depression 

 and central eminence which Prof. Jaeger describes in the large tooth 

 of his species ; this difference might, however, be due to the mode 

 in which the tooth had been used or worn down. 



The main point to be determined was whether and to what extent 

 the apparently simple conical tooth from the English sandstone would 

 correspond with that of the German Batrachian in the complicated struc- 

 ture above described. I could perceive indications, at the fractured basis 

 of the Warwick tooth of fissures leading from the external striee into 

 the substance of the tooth. Were these fissures continued to the same 

 extent, or in the same sinuous course which they had presented in the 

 tooth of the Labyrinthodon Jaegeri ? This could not be ascertained by 

 inspection of the fractured surfaces of the dense and opake tooth either 

 by unaided vision or the use of the microscope by reflected light. 



