. Bulletin of the British Museum (Natural History), Geology. LATE CAMPANIAN-MAASTRICHTIAN ECHINOIDS 199 The periproct lies on the posterior face, relatively high in juveniles but becoming progressively lower in larger speci- mens (Fig. 56). The base of the periproct lies 50% of test height above the base in small individuals, but can lie as low as 22% of test height in the largest individuals. There is, however, considerable variation in the height of the periproct within the sample. The periproct is relatively small and taller than wide (height = 1-3-2-5 times greater than width). Typically,
. Bulletin of the British Museum (Natural History), Geology. LATE CAMPANIAN-MAASTRICHTIAN ECHINOIDS 199 The periproct lies on the posterior face, relatively high in juveniles but becoming progressively lower in larger speci- mens (Fig. 56). The base of the periproct lies 50% of test height above the base in small individuals, but can lie as low as 22% of test height in the largest individuals. There is, however, considerable variation in the height of the periproct within the sample. The periproct is relatively small and taller than wide (height = 1-3-2-5 times greater than width). Typically, there is a slight adapical projection and rim devel- oped around the periproct. Tuberculation is fine and uniform aborally and slightly coarser adorally. There is a narrow sternal naked zone on the oral surface behind the peristome. Remarks. This species was first described from the 'Upper Senonian' (probably Maastrichtian) of Derre-i-Chahr, southern Iran, by Cotteau & Gauthier (1895: 60) under the name Catopygus morgani. Cotteau & Gauthier distin- guished it from other similar species by its inflated shape and convex oral surface. Although their figure indicates a peristome that is as broad as long, in all other respects it falls exactly within the range of the United Arab Emirates population described here (Fig. 57). Should the Iranian population prove to have a consistently more equant peristome, then it clearly should be treated as a distinct species. However, the figures cannot be considered entirely reliable and this difference is not apparent in topotype material (PI. 21, figs 10-13). Consequently, for the present the two forms are synonymized. In 1906 Krumbeck erected the species Catopygus rohlfsi on the basis of a specimen from the late Cretaceous of Libya. Closely comparable material from Algeria was given the name Catopygus boucarti by Lambert & Thiery (1925). Based on a large collection of specimens from the Maastrichtian of Libya, Airaghi (1939) was lat
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