. Bulletin of the British Museum (Natural History), Geology. THE OLD RED SANDSTONE OF BROWN CLEE HILL 271 upper surface contained about four and a half times in that of dorsal shield; dorsal disk with maximum breadth somewhat less than median length and narrowing only moderately towards anterior end. Dentine ridges of superficial " ornamenta- tion " coarse, average 5-6 per mm., when unworn A-shaped with relatively coarse lateral denticulations continued on to the ridges, giving a crenulate appearance. Holotype. An imperfect dorsal shield (). Material. In addition to the holoty
. Bulletin of the British Museum (Natural History), Geology. THE OLD RED SANDSTONE OF BROWN CLEE HILL 271 upper surface contained about four and a half times in that of dorsal shield; dorsal disk with maximum breadth somewhat less than median length and narrowing only moderately towards anterior end. Dentine ridges of superficial " ornamenta- tion " coarse, average 5-6 per mm., when unworn A-shaped with relatively coarse lateral denticulations continued on to the ridges, giving a crenulate appearance. Holotype. An imperfect dorsal shield (). Material. In addition to the holotype, about 70 specimens, including a dorsal disk ; one almost complete and two fragmentary ventral disks; three incomplete branchial plates ; 34 isolated scales and about 30 other Fig. 17. Protaspis (Europrotaspis) crenulata sp. nov. A, B, C, three fragments of different rostra, ventral view, with median longitudinal section of centre fragment, showing the pre-oral field (PF). Besom Farm Quarry. , , respectively, x 2-25. Localities. The most important is the old quarry \ mile SE. of Besom Farm, Wheathill, Shropshire ; another is Upper Overton Quarry, nearly 5 miles to the north-east. Exposures at Prescott Reaside and Far low Brook Bridge have also yielded some good specimens. Scales and fragments have been found at three or four other places in the neighbourhood. Description. The holotype is an eroded and primarily imperfect dorsal shield (Text-fig. 16). The right side of the rostrum and most of the right orbital plate were lost before fossilization, and subsequently almost the whole of the dorsal disk and the dorsal side of the right branchial have been removed by weathering, the specimen being on a loose surface block. The left branchial plate with the minute cornual is very well preserved, the posterior half being uncrushed (as was presumably the whole specimen) and preserved in the round. An interesting feature of this specimen is the occurr
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