. Bulletin of the British Museum (Natural History), Geology. CRETACEOUS ECHINODERMS FROM WILMINGTON 59. 1mm Fig. 19 Camera lucida drawing of the apical disc of Goniophorus lunulatus () from Wilmington. Ocular III to the top. plates per column at 4 mm test diameter, and 5-6 plates from 6 to 10 mm test diameter. All interambulacral plates have a single large tubercle and plate height and plate width are more or less equal at the ambitus (height is on average 98% of the width; SD = 005; N = 18). The primary tubercle occupies most of each plate and is surrounded by a narrow circle of genera
. Bulletin of the British Museum (Natural History), Geology. CRETACEOUS ECHINODERMS FROM WILMINGTON 59. 1mm Fig. 19 Camera lucida drawing of the apical disc of Goniophorus lunulatus () from Wilmington. Ocular III to the top. plates per column at 4 mm test diameter, and 5-6 plates from 6 to 10 mm test diameter. All interambulacral plates have a single large tubercle and plate height and plate width are more or less equal at the ambitus (height is on average 98% of the width; SD = 005; N = 18). The primary tubercle occupies most of each plate and is surrounded by a narrow circle of generally five small secondary tubercles, which are arranged in such a way that those on adjacent plates alternate, forming a more or less continuous zig-zag row interradially (PI. 6, fig. 3). Adorally, the secondary tubercles become arranged into two discrete rows but never have miliary tuber- cles between the rows. The areole is circular and forms about 80% of the plate width ambitally. The boss is tall and steep-sided, and is surmounted by a very small, imperforate tubercle that is only about 16% of the plate width (SD = 2-7; N = 18). Tubercles are weakly crenulate. There are 5-6 ambulacral pores adjacent to ambital interambulacral plates in small individuals and 6-7 in larger specimens. PERISTOME. This is small and circular in outline, and only very slightly sunken. In diameter it is 30-43% of the test diameter (mean = 37%; SD = 3-8; N = 18). Buccal slits are present, although fairly small, and are bounded by a sharp rim. Remarks. This very distinctive species was properly described and figured by Agassiz (1838) and there has been little taxonomic confusion over it. Although previous authors have sug- gested that its ambulacral pores were simple throughout, the most adoral plates are undoubtedly bigeminate. Each pair of plates has a single large primary tubercle and, adorally, a deep, circular sphaeridial pit. The circular pits are better developed in this species than in any oth
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