The Echinoid Directory

• Test ovate in outline with slightly truncated posterior margin, greatest width and height posterior to centre. Margins thick and rounded.
• Apical system anterior, tetrabasal, with four genital pores, no catenal plates.
• Petals of equal length, with outer pore-pair more elongate than inner, all ambulacral plates with double pores.
• Periproct towards the rear of the aboral surface; supramarginal, on an almost vertical face, close to the margin, with a short groove extending from lower edge of periproct to posterior edge of test.
• Peristome anterior, pentagonal, slightly higher than wide; with inturned lip forming entrance to the opening.
• Bourrelets slightly developed.
• Phyllodes slightly broadened, with two series of double pores in each half-ambulacrum.
• No differentiated buccal pores.

Upper Jurassic (Kimmeridgian) to Upper Cretaceous (Cenomanian) of Europe, India and United States according to Kier (1962).

• P. gresslyi (L. Agassiz, 1839); Valanginian-Hauterivian, England and Europe.
• P. neocomiensis (d'Orbigny, 1854); Valanginian, France and Switzerland.
• P. humilis (Gauthier, 1875); Valanginian, Algeria.
• P. fourtaui (Lambert, in Demoly, 1913); Upper Valanginian, France.
• P. requieni (Desor in Agassiz & Desor, 1847); Urgonian, France.

Lambert & Thiery (1909-1925) list 23 species within this genus.

Irregularia; Neognathostomata; \'nucleolitid\'.

Phyllobrissus is intermediate in appearance between Nucleolites and Catopygus and Kier (1962, p. 76) states that it is difficult to decide whether or not this genus should be maintained. All have the same petal arrangement, very similar phyllodes, with two series of pore-pairs in each half-ambulacrum and with the inner pore of each pair greatly reduced in size. For this reason Lambert (1902, p. 15) and Mortensen (1948, p. 167) suggested that Phyllobrissus might be considered a subgenus of Catopygus. Kier (1962, p. 76) points out that Phyllobrissus gresslyi is slightly broader, with a more depressed adapical surface, and an obliquely truncated posterior margin, exposing the periproct adapically. In Catopygus carinatus the posterior margin is pointed, and the periproct not visible from above. However, Kier (1962, p. 76) adds that although these differences may be sufficient to distinguish these genera, there are some species that have some of the characters of both type species, making it very difficult to decide to which of the two genera to assign them.

Phyllobrissus is similar to Nucleolites, both having narrow, straight, open petals and very similar phyllodes. Kier (1962, p. 76) suggests that Phyllobrissus differs in having a more elongate test, more developed bourrelets, and a more marginal periproct. We tentatively consider the more marginal periproct, on an almost vertical face, with only a short groove extending from the lower edge of the periproct to the posterior edge of the test, worthy of generic distinction.

Cotteau, G. 1857-1878. Études sur les échinides fossiles du Département de l’Yonne. Volume 2. Terrain Crétacé. Paris. 518 pp., 38 pls. [Reprinted and repaginated from Bulletin de la Société des Sciences historique et naturelles de l’Yonne 1857-1878: (1857) 11, 401-433, pls 47-50; (1858) 12, 485-522, pls 51-54; (1859) 13, 425-457, pls 55-58; (1860) 14, 327-355, pls 59-62; (1863a) 17, 3-39, pls 63-64; (1863b) 17, 165-195, pls 65-66; (1865) 19, 195-263, pls 67-70; (1876) 30, 47-103, pls 71-76; (1878) 32, 193-280, pls 77-84].

J. Lambert & P. Thiery. 1909-1925. Essai de nomenclature raisonnee des echinides. Libraire Septime Ferriere, Chaumont, 607 pp., 15 pls.

P. M. Kier. 1962. Revision of the cassiduloid echinoids. Smithsonian Miscellaneous Collections, 144 (3) 262 pp.

T. Mortensen. 1948. A monograph of the Echinoidea: 4 (1): Holectypoida, Cassiduloida. Reitzel, Copenhagen, 363 pp., 14 pls.