of Terebratulina and Waldheimia. 17 



margins crenulate. In the dorsal valve there is no indication 

 of a mesial septum ; the socket-ridges are strong and well 

 developed. Length 3| lines, width 2f lines, depth \\ line. 



Ohs. I beg to name this beautiful little shell after Mr. T. 

 Davidson, to whom, as previously stated, I am under many 

 obligations. Although all the internal portions of the dorsal 

 valve are not preserved, the entire absence of the mesial 

 septum, with the characters of the beak in the ventral valve, 

 appear to indicate this as a species of Terebratulina. 



Loc. and Horizon. Coralline Limestone of Mount Gambler, 

 S. A. Coll. Geol. Soc. Loud., presented by the Rev. J. E. 

 Woods. 



Subgenus Waldheimia, King. 



Waldheimia Garihaldiana, Davidson. (PI. I. figs. 2a&b.) 

 TV. Garibaldiana, Dav., The Geologist, 18G2, v. p. 446, t. 24. f. 9. 



Si), char. Shell obscurely pentagonal, with the lateral 

 margins flexuous, and the ventral valve the more convex of 

 the two. Ventral valve convex and rather deep, divided into 

 three portions by two diverging ridges or ribs, which com- 

 mence close to the extremity of the beak, and extend to tlie 

 front, leaving between them a slightly concave or flattened 

 space resembling a broad and depressed keel, in which three 

 or four longitudinal ribs are to be seen ; the lateral portions of 

 the valve become gradually and gently concave as they ap- 

 proach the margins, and are obscurely wrinkled by a few 

 longitudinal or, more properly speaking, curved ribs ; beak 

 produced, incurved, and truncated by a slightly oblique fora- 

 men, separated to some extent from the hinge-line by a 

 deltidium. The dorsal valve is also divided into three por- 

 tions, the central space being flattened and furrowed by three 

 or four longitudinal obtusely rounded ribs, while the lateral 

 portions become more elevated as the front is approached, and 

 are ornamented by six or seven curved ribs, which become 

 somewhat obscured as they approach the margin of the shell. 

 Interior unknown. Length 1 inch 7 lines, width 1 inch 

 3 lines, depth 10 lines. 



Obs. The above is Mr. Davidson's excellent description of 

 this handsome shell almost in his own words. When ori- 

 ginally described, W. Garibaldiana was supposed to have 

 come from the Tertiary beds of Malta ; but Mr. Davidson 

 afterwards satisfied himself that it in reality came from Mount 

 Gambicr. Tho nature of the matrix filling the valves bears 

 out this view, if matrix can be accepted as a test ; for it agrees 

 exactly in lithological character with that adhering to authen- 

 ticated specimens from the same locality. Mr. Davidson 



Ann. (k Mag. N. Hist. Scr. 4. Vol. xvii. 2 



