1854.] OWEN PURBECK FOSSILS. 421 



of the inner wall (fig. 2) is from 3 to 4 lines. The exterior surface 

 of the bone is smooth and polished, but impressed by very fine, lon- 

 gitudinal linear markings, and perforated by nervous or vascular 

 foramina along the alveolar wall : it is traversed near the lower mar- 

 gin by a line answering to the suture dividing the dentary from the 

 angular piece in the jaw of the Varanus. The ramus is compressed 

 (fig. 3), scarcely 2 lines across at its thickest part, but it has been 

 slightly crushed. 



The enamelled crowns of the teeth are moderately long, slender, 

 compressed, pointed, slightly recurved, and with a well-marked serrated 

 margin both before and behind (fig. 4, magnified) : they are thickest 

 towards the anterior part, as in the Megalosaurus, and closely re- 

 semble, in miniature, the teeth of that great carnivorous reptile. 



The present fossil differs, however, from the Megalosaurus in 

 having the inner alveolar ridge of the jaw not more developed than 

 in the modern Varani, and in not exhibiting any rudiments of 

 alveolar divisions ; the bases of the teeth, which are anchylosed to 

 the outer wall, being completely exposed on the inner side of the jaw 

 (fig. 2.) In the two largest teeth, d, e, which are 2 lines in diameter at 

 their base, that base is excavated on the inner side through absorp- 

 tion caused by pressure of the matrix of a successional tooth. A 

 young tooth, c, straighter and more conical than the rest, which has 

 thus displaced its predecessor, is rising up between the two old teeth 

 above described. The first and second teeth, a & ^, in this fragment are 

 fully formed, are entire, and show well the normal characters of the 

 crown. At the opposite end of the series was the crown of a young 

 tooth which had not risen above the outer alveolar wall. The crowns 

 of the teeth are of a dark grey colour, marked with transverse bands 

 of lighter grey. 



The entire of this interesting fragment gives evidence of a carni- 

 vorous or insectivorous Lizard of the size of the VaravMs crocodilinus, 

 or great Land Monitor of India*. The specific name relates to the 

 formidable adaptation of its teeth for piercing, cutting, and lacerating 

 its prey. 



In a block of the laminated marly bed of the Purbecks, contain- 

 ing shells {Cyclas and Planorbis), transmitted by Mr. Willcox, are 

 imbedded some fragments of bony scutes, and the major part of a 

 tibia and fibula of a small Saurian reptile (fig. 5), agreeing in size 

 with the species indicated by the above-described portion of jaw. 

 The length of the portion of tibia preserved is 1^ inch, and the im- 

 pression of the shaft extends 3 lines longer : about the same length 

 is indicated of the fibula by the bone and its impression. The dia- 

 meter of the shaft of the tibia is 1^ line ; and the proportion of the 

 length to the breadth of both bones is greater than in any known 

 recent form of Lizard or Crocodile. The species to which the bones 



* See my ' Odontography,' p. 265. pi. 68. fig. 3 ; fig. 3' gives a magnified view 

 of the crowTi of a tooth of this species, showing its resemblance to the fossil. The 

 specimen above described was obtained at the Feather Quarry, and from the divi- 

 sion of the Chert-beds marked J. 81-84. in the stratigraphical list in the Rev. Mr. 

 Austen's ' Guide to the Geology of the Isle of Purbeck,' Svo. Blandford, 1852. 



