168 Miscellaneous. 



beds, and was rewarded by the discovery of several interesting fos- 

 sils, among them the lower jaw of a small mammal. This speci- 

 men indicates a diminutive marsupial, quite distinct from the one 

 previously described by the writer from the same horizon (Dryolestes 

 priscus)*, which has hitherto been the only mammal known from 

 the Jurassic of this country. 



The present specimen, which is from the left side, has the larger 

 part of the ramus preserved, with a number of perfect teeth in 

 position. Most of the symphysial portion is lost, and the posterior 

 part is missing or only faintly indicated. The jaw was remarkably 

 long and slender. The horizontal portion is of nearly equal depth 

 throughout, and the lower margin nearly straight. The form of 

 the coronoid process, condyle, and angle of the jaw cannot be deter- 

 mined from this specimen. 



The remarkable feature in this jaw is the series of premolar and 

 molar teeth. These were very numerous, apparently as many as 

 twelvo in all, and possibly more. The premolars had their crowns 

 more or less compressed and recurved ; and some of them wero sup- 

 ported by two fangs. These had a small posterior tubercle at the 

 base of the crown, but none in front. Tho molar teeth were all 

 single-fanged, with elevated conical crowns ; those preserved have 

 a distinct cingulum. The molars increase in sizo from the first to 

 the fifth. All the teeth preserved have the crowns raised consider- 

 ably above the upper margin of the jaw, and thus appear to be 

 loosely inserted. A large pointed tooth lying near the jaw appears 

 to be a canine. 



The principal dimensions of this specimen are as follows : — 



millim. 



Length of portion of jaw preserved 11*5 



Extent of five molar teeth 4-0 



Extent of entire molar series 5*0 



Height of fifth true molar above jaw 2*0 



Depth of jaw below fifth molar l - 75 



Depth of jaw below last premolar 1*5 



Depth of jaw below first premolar 1*4 



In comparing this interesting fossil with the forms already 

 known, it is at once evident that it differs widely from any living 

 type. Its nearest affinities are clearly with the genus Stylodon of 

 Owen, from the Purbeck beds of England f ; and in many respects 

 the correspondence is close. 



This specimen clearly indicates a new genus, which may be called 

 Stylacodon, and the species represented Stylacodon gracilis. With 

 the genus Stylodon, this form evidently constitutes a distinct family, 

 which may appropriately be termed the Stylodontida). The present 

 specimen indicates an animal somewhat smaller than a weasel, and 

 probably insectivorous in habit. — Amer. Journ. Sci. Sf Arts, July 

 1879. 



* 'Annals,' July 1878, p. 108. 



t Geological Magazine, vol. iii. p. 199 (1866), and ralseoutograplncal 

 Society, vol. xxiv. p. 45 (1871). 



