BELEMNITES OF THE OOLITE. 107 
BELEMNITES ARIPISTILLUM, Liwyd. Pl. XXVI, fig. 64. 
Reference. Belemnites aripistillum referens, Liwyd, ‘ Lithophylacium Britannicum,’ 
No. 1705, pl. xxv, fig. 1705, 1699. 
Fusiform Belemnite, Platt, ‘ Pnil. Trans.,’ pl. iv, fig. 2, 1764. 
B. fusiformis, Parkinson, ‘Org. Rem.,’ p. 127, vol. 1, pl. vii, fig. 13, 1813. 
B. fusiformis, Miller, ‘Geol. Trans.,’ p. 61, vol. u, pl. vin, fig. 22; 
pl. ix, figs. 5, 7, 1826. 
B. fusiformis, Morris and Lycett, ‘ Great Oolite Mollusca,’ Part. I, p. 8, 
pl. 1, figs. 6 and 8, 1851. 
i) Guarp. Elongate, fusiform, anteriorly circular, posteriorly depressed, with a deep 
E well-defined furrow on the ventral surface, extending over the alveolus, and reaching to 
- the apex, or near to it. 
The young and old agree in general form. 
Transverse sections show the outline to be reniform in all the post-alveolar region, 
the longest diameter being from side to side; in the most advanced part of the alveolar 
region the section is nearly circular; the axis is excentric and straight. 
The longest specimen of the guard, including its expansion over the alveolus, measures 
3} inches ; the alveolar portion being $ inch. Diameter from side to side at the alveolar 
apex “21, at the expanded part ‘36. 
Proportions. ‘Taking the diameter from back to front at the alveolar apex at 100, 
that from side to side is 120, the axis 1000. 
Puracmocone. Partially observed in several specimens, in none completely. 
Locality. Stonesfield, Oxfordshire (Pdc//ips) and Eyeford, Gloucestershire (Buck- 
man); in the lowest fissile beds of the Great Oolite. 
Observations. Morris and Lycett (‘ Pal. Soc. Monog.’) and Morris (‘ Catalogue of 
British Fossils’) give for a synonym B. Fleuriausus of D’Orbigny, ‘Terrains Jurassiques 
Céphalop.,’ pl. xiii, figs. 14—18. D’Orbigny himself treats B. fusiformis as identical with 
B. hastatus—remarking of this species the unusual distance between the septa, the apex 
submucronate and free from groove for one third of the apicial length, and the small 
angle of the phragmocone (11° to 18°). “Itis,” he says, ‘‘ without contradiction, the most 
characteristic species of the lower Oxford Clay, where it constitutes a positive and certain 
zone.’ If we take the drawings and descriptions of D’Orbigny for guide, and compare 
with them the fossils of British localities, we shall find in the Oxford Clay of Cowley near 
Oxford, close analogies to B. astatus, and in the fossils of Stonesfield equal resemblance 
to B. Fleuriausus, which is quoted from “ Great Oolite” at Lucon (Vendée). 
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