. Bulletin of the British Museum (Natural History), Geology. BRITISH WEALDEN SHARKS 317 Description. In this subspecies the form and proportions of the teeth do not differ significantly from those in L. breve breve. The largest tooth (Text-fig. 17c) is 3-5 mm. long, similar in size to the largest L. breve breve. The occlusal crest of the teeth is produced into a number of small and irregular lateral cusps or beads. Both the Ungual and labial faces of the crown bear a number of weak, parallel, vertical striae, the striae being strongest at the central cusp. Both the beading of the occlusal cres
. Bulletin of the British Museum (Natural History), Geology. BRITISH WEALDEN SHARKS 317 Description. In this subspecies the form and proportions of the teeth do not differ significantly from those in L. breve breve. The largest tooth (Text-fig. 17c) is 3-5 mm. long, similar in size to the largest L. breve breve. The occlusal crest of the teeth is produced into a number of small and irregular lateral cusps or beads. Both the Ungual and labial faces of the crown bear a number of weak, parallel, vertical striae, the striae being strongest at the central cusp. Both the beading of the occlusal crest and the striation of the crown are weakest in the short, deep anterior teeth (Text-fig. 17A), strongest in the longer, lower lateral and posterior teeth. Remarks. This subspecies is commonest in the Paddockhurst bone-bed, where it accounts for about half of the specimens of Lonchidion breve, the other half being L. breve breve. The fact that teeth of L. b. crenulatum from this horizon exhibit the same range of size and shape as those of L. b. breve (cf. Text-figs. 15, 17) and the ab-. / mm Fig. 18. Lonchidion breve crenulatum sp. et ssp. nov. , a tooth from the Wadhurst Clay; Ashurstwood, Sussex, in labial (above), occlusal (centre) and lingual view. sence of L. b. crenulatum at Cliff End and in the Telham bone-bed show that the two subspecies are distinct forms, not teeth from different parts of the mouth of the same fish. L. b. crenulatum is not known above the Grinstead Clay. In a sample of four teeth of Lonchidion from the Wadhurst Clay at Ashurstwood, Sussex, three are L. b. crenulatum (Text-fig. 18) and one is L. b. breve. L. b. crenidatum does not occur in the large sample of Lonchidion from the Cliff End bone-bed in the Ashdown Beds or the Telham bone-bed at the base of the Wadhurst Clay, nor is it known in the Purbeck, although the posterior teeth of L. heterodon (Text-fig. 25c) are very like it. In spite of this resemblance, it seems probable that L. b. crenu
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