Page:Quarterly Journal of the Geological Society of London, vol. 26.djvu/367

MOORE AUSTRALIAN MESOZOIC GEOLOGY. 259 Belemnites, is not longer than in youth, and its proportion to the diameter is reduced to 240 : 100.

These fossils appear on the whole most allied to Belemnites hastatus of Blainville, and to the depressed variety of it which occurs in the Oxford Clay of England. But they are entirely distinct by the lateral grooves being so sharply cut over the alveolar and postalveolar region, and by the absence of ventral groove.

There is, indeed, one specimen (the posterior part of a large guard) marked Upper Maranoa river, which, with portions of the lateral grooves, shows along the ventral face a partially impressed but interrupted groove, not unlike some appearances on Belemnites sulcatus of the Oxford Clay of England. The lateral grooves show ramifications, and appear not to bend backward. It may be a different but allied species.

Finally there is a small nearly cylindrical Belemnite, with a subcentral axis and an acute-angled alveolar cavity. It has one long narrow groove, not clearly seen to be a ventral groove. Though incompletely exhibited, it must be a distinct species from the others. It is marked Upper Maranoa. It is not one of the Canaliculati, but more probably one of the Hastati. — J. P.

Since the above notes were made by Professor Phillips, I have succeeded in opening up two imperfectly exhibited specimens in a block from Wollumbilla (P1. XVI. fig. 6), respecting which he remarks "that they belong to young Belemnites and show the phragmocone in situ, and the straight nearly central axis of the guard, with a small canal. The cross section of the phragmocone is distinctly elliptical and oblong ; the siphuncle is clearly enclosed ; longitudinal dorsal striae very distinct. I have made a sketch of these points, which on the whole make me adhere to the opinion of the Oolitic, and perhaps Liassic, affinity of this shell. It appears to be most nearly allied to B. paxillosus, but to be distinct by its elliptical phragmocone : this ellipticity diminishes with age."

DESCRIPTION OF PLATES X.-XVIII.

(All the figures are of the natural size, except where stated to be otherwise.)

Plate X.

Fig. 1. Terebratella Davidsonii, Moore, dorsal valve.

2. The same, ventral valve.

3. Argyope wollumbillaensis, Moore, dorsal valve, enlarged one- half.

4. The same, ventral valve, enlarged one-half.

5. The same, interior of dorsal valve.

6. A. punctata, Moore, dorsal valve, enlarged.

7. Rhynchonella rustica, Moore, dorsal valve.

8. The same.

9. The same, ventral valve, younger specimen.

10. R. solitaria, Moore, ventral valve.

11. R. variabilis, Schloth., dorsal valve, rather enlarged.

12. The same, ventral valve, rather enlarged.

13. Discina apicalis, Moore, enlarged.

14. Lingula ovalis, Sow.

15. Natica variabilis, Moore.