498 A. j. jukes-browne's supplementary
doubt of this identity ; those from the Perte du Rhone which retain the shell agree entirely with Mr. Seeley's type, which has the shell converted into phosphate of lime, and is preserved in Mr. Carter's collection.
D'Orbigny's figure does not express the rugose lamellae under- neath, which coexist with the striae said to be characteristic ; the nodules also are made too regular and too distinctly double, whereas they are only elongated or bilobed.
Mr. Seeley's figure of the under surface is very good ; but the side view gives too high an elevation, and the base is badly drawn ; the nodulations, again, are too distinctly single ; on the specimen itself they are more irregular, more elongate, and may have been bilobate. The side view of this and also of a Rhone specimen are given in PI. XXII. figs. 3 & 5.
Those from the Perte du Rhone vary much in height, some having the elevation of T. nodosa, others being low and resembling that called T. eoopansa by Mr. Seeley. One individual of the Cambridge T. expansa shows protuberances on the cast caused by the tuber- culations of the shell : they are probably only varieties of the same species.
Trochus cancellatus, Seeley.
Comp. Turbo indecisus, D'Orb. Pal. Fr. p. 230.
I think MM. Pictet and Campiche must have been mistaken in referring any Cambridge specimens to T. Tollotianus. I have recently had an opportunity of comparing them with specimens from the Perte du Rhone ; and though these are somewhat similar to T. cancelled us in shape, yet they are quite smooth, showing neither spiral lines nor cancellated markings ; neither is there any trace of the occasional varices.
I am inclined to think therefore that Trochus cancellatus is a distinct species, and that T. ToHoticums does not exist in the Cambridge Greensand. I may mention that it was by a mistake that the latter name was inserted in the Explanation of plate xiv. appended to my former paper (Quart. Journ. Geol. Soc. vol. xxxi. p. 313).
[Since writing the above I have seen the collection of D'Orbigny's types at the Jardin des Plantes in Paris : and among these I found specimens named Turbo indecisus, which appear identical with T. cancellatus ; one of them shows the longitudinal markings, and another the full cancellations, in the same variable way as the Cam- bridge casts exhibit them. D'Orbigny, p. 230, says that it occurs at Eocragnoles, Perte du Rhone, and Clansaye, but that he only knew the internal cast.]
Natica levistriata, new sp. PI. XXI. fig. 6.
Shell globose ; spire moderately high : whorls flattened above, so as to produce a slight angulation which runs round the spire : below this on the body- whorl there are 10 or 11 slightly elevated spiral striae. The angulation may be otherwise described as the highest
