106 



A.B. SMITH ETAL. 



mens are, however, too poorly preserved to form the basis for 

 formally erecting a new species name. 



Order HOLASTEROIDA Durham & Melville, 1957 



Diagnosis. Irregular echinoids with meridosternous or 

 orthostemous plastron, paired ambulacra flush on test; apical disc 

 elongate with one or both ocular plates inserted between anterior and 

 posterior pairs of genital plates. 



Family HOLASTERIDAE Pictet, 1857 

 Genus OFFASTER L. Agassiz, 1836 



Diagnosis. Small holasteroids with flat to slightly convex base 

 and vaulted upper surface. Apical disc with four gonopores. Frontal 

 groove absent aborally, slightly depressed at ambitus and 

 subambitally, at least in small individuals. Peristome oval to D- 

 shaped; facing downwards, with little or no labral projection. Plastron 

 meridosternous with first two to three plates uniserially arranged. 

 Periproct on posterior face. Marginal fasciole present, at least in 

 juvenile stages; possibly absent in larger individuals. 



Offaster leymeriei CottesLU, 1887 



PI. 4, figs 10-13; Figs 14, 15 



1887b 



Offaster Leymeriei Cotteau: 661, pi. 19, figs 14, 15, pi. 20, 



figs 1-3. 

 71927 Ojfaster dallonii Lambert: 43, pi. 3, figs 12-15. 

 1992 Ojfaster dallonii Gallemi: 257, photo 14. 

 1996 Ojfaster dallonii Wilmsen et al.: fig. 7. 



Diagnosis. Test up to 30 mm in length; width ca. 80-85% length; 

 height ca. 65% of length. Ovate in outline; specimens larger than 

 about 15 mm with convex anterior, smaller individuals with slight 

 anterior sulcus developed from ambitus adorally. Peristome moder- 

 ately large, oval, 15% test length from the anterior. Periproct large, 

 occupying the upper part of the posterior face, which slopes very 

 slightly inwards so that the periproct is just visible from below but 

 not from above. Plastron plating meridosternous. Tuberculation 

 relatively fine, with no primaries differentiated aborally. Small indi- 

 viduals show a clear marginal fasciole around the posterior margin of 

 the test; this fasciole may be lost in large individuals. 



Occurrence. Maastrichrian, horizons 3 and 5, Santander. 

 Maastrichtian, horizons 5 and 6, Olazagutia Pass, Navarra. Lower 

 Maastrichtian, Homes Morts Member, Salas de Pallars, Tremp Basin 

 (Gallemi, 1992). The type comes from the Upper Cretaceous 

 (?Maastrichfian) of Roquefort, Haute-Garonne, France. 



Material studied. BMNH EE6 170-72, EE6263-64, MGB 

 37459, 37543, 37548-49. 



Remarks. This species was originally placed in Offasterby Cotteau 

 ( 1 887b) and Lambert ( 1 927), but differs from the type species of that 

 genus, O. pilula (Lamarck), in lacking a clear marginal fasciole, as 

 originally pointed out by Lambert when setting up this species. O. 

 pilula and O. leymeriei both have rather rudimentary aboral pores 

 and have almost no anterior sulcus. We have found that small 

 individuals (<15 mm) have a clearly developed marginal fasciole 

 and that this is largely lost during growth. These small individuals 

 also have a slight anterior sulcus developed from the ambitus adorally, 

 like O. pilula. 



Cotteau (1887b) erected the species Ojfaster leymeriei on the 



Fig. 14 Camera lucida drawing of plating in Ojfaster leymeriei Cotteau, 

 1 887 from the Maastrichtian of the coast west of Cabo Mayor 

 (Santander, Cantabria); MGB 37549, apical disc. Scale bar = 1 mm. 



basis of a 30 mm individual from the Upper Cretaceous 

 (?Maastrichtian) of Roquefort, Haute-Garonne, France. Lambert 

 (1927) subsequently erected the species O. dallonii from the 

 Maastrichtian of Sapeira, near Tremp, Catalonia. Lambert compared 

 his species with Cotteau's and separated dallonii on the grounds that 

 it was smaller, a little less elongate, its lower face less flat, its 

 peristome more anterior and opening not within a depression, but 

 slightly raised, its periproct is slightly higher and its ambulacral 

 plates are less tall and the pore-pairs are more closely spaced. We 

 have not been able to study Cotteau's type material, but suspect that 

 the differences cited by Lambert are more apparent than real and 

 derive largely from the artistic rendition of the specimens in ques- 

 tion. In any case, topotype material of O. leymeriei from Roquefort 

 (BMNH E9465) is indistinguishable from our material from both 

 Tremp and Santander. 



Genus CARDIASTER Forbes, 1850 



Diagnosis. Cordiform in outline. Petals distinct, though small, 

 with asymmetric columns, the posterior columns being slightly 

 narrower than the anterior columns. An anterior sulcus runs from 

 apex to peristome, and is deepest at the ambitus. Plastron plating 

 biserial after the initial two or three plates. A marginal fasciole is 

 developed around posterior and lateral parts of the test. 



Cardiaster sp. 



PI. 4, fig. 19; Fig. 16 



Diagnosis. Test up to40 mm in length, width about 85% of length, 

 cordiform in outline with distinct anterior groove; tapering to a blunt 

 point posteriorly. Upper surface with median ridge and sloping 

 sides; disc plating not preserved in either specimen. Petals flush; 

 columns of pore-pairs unequal, with posterior series better devel- 

 oped than anterior series pores. Pore-pairs not joined by conjugate 

 groove and the two pores are angled to each other. Peristome slightly 

 depressed, kidney-shaped. Plastron broad, with biserial plating fol- 

 lowing a triangular labral plate. Periproct posterior. Fascioles not 

 present around the anterior margin; elsewhere, test preservation too 

 abraded to tell. Larger aboral tubercules lie along the margins of the 

 anterior groove and a few are also present adapically. 



