Page:Quarterly Journal of the Geological Society of London, vol. 33.djvu/223

	T. robusta.	R. C. S. No. 1021 b.	T. ephippium.
	millim.	millim.	millim.
Length by callipers ................................................................................................................................................................................................................................................................................................................................................................................................	66	60	43
Length by tape ................................................................................................................................................................................................................................................................................................................................................................................................	92	82	60
Breadth by callipers ................................................................................................................................................................................................................................................................................................................................................................................................	55	50	35
Breadth by tape ................................................................................................................................................................................................................................................................................................................................................................................................	72	70	52

I have given the chief measurements of fig. 4 in my former paper. Suffice it to state, as to the comparative dimensions, that the fossil exceeds in size any recent femur I have been enabled to examine, and shows that the owner was a gigantic tortoise, but possibly not quite so large as the owner of the coracoid just described.

A distal extremity of a right femur, comparable as regards dimensions with the form to which I assign the name of T. Spratti, is also from Mnaidra Gap. It is relatively small as compared with the same part in the immature skeleton (No. 1011 of the Museum of the Royal College of Surgeons) referred by Günther to T. elephantopns^[1]. The breadth of the condyles in the last is 78 millimetres, whereas it is only 56 in the fossil. In the latter there is a shallow depression above the condyles superiorly, and a deep pit at the same point on the opposite or inferior side. The condyles are stouter relatively and more confluent than in T. ephipphium, and more like what obtains in T. vicina; the specimen, however, is too fragmentary for precise determination.

The small right femur from Zebbug (Plate VI. figs. 5, 5a, 5b) has lost its distal extremity. The head is elliptical, and confluent with the great trochanter, and is at the same level. The great trochanter (fig. 5a), as in the large femur, is separated by a deep notch from the lesser trochanter, the enclosed pit (fig. 5b) being almost circular. The largest diameter of the head is 12 millimetres, and the least girth of the shaft is 18 millimetres. In T. græca there is no notch, the shaft is less bent, and the trochanters are more convergent. Although somewhat larger than a femur of Lutremys europæa (46 millimetres in length), it agrees with it in every respect, in common with the humerus (fig. 6), both of which therefore may be accepted provisionally as belonging to that species.

 

Tibia.

The two tibiæ, right and left (Plate V. figs. 3, 3a, and Plate VI. figs. 4, 4a) are from Zebbug. The larger, or right tibia (Plate V. fig. 3), is not entire, having lost portions of the head on its outer

1. Op. cit. p. 261.