LATE CRETACEOUS-EARLY TERTIARY ECHINOIDS 



107 



Fig. 15 Camera lucida drawing of plating in Offaster leymeriei Cotteau, 1 887 from the Maastrichtian of the coast west of Cabo Mayor (Santander, 

 Cantabria). BMNH EE6170. a, apical surface; b, oral surface. Interambulacra shaded. Scale bar = 5 mm. 



Occurrence. 

 ince, Spain. 



Upper ThanetianofCasasdeOraien,Navarraprov- Hemipneustes striatoradiatus (Leske, 1778) 



Material studied. B MNH EE6 1 74-75 . 



Remarks. Although both specimens are incomplete, the cordi- 

 fonn outline and distinctive plastron plating are indicative of just two 

 holasteroid taxa, Cardiaster or Pseudholaster. Cardiaster has the 

 labral plate and first sternal plate arranged uniserially, whereas 

 Pseudholaster has the labral plate extending to touch the outer edge 

 of the second labral plate. Furthermore, Cardiaster has a marginal 

 fasciole that disappears towards the anterior, whereas Pseudholaster 

 has no fascicles whatsoever. Unfortunately, preservation is so poor 

 that the presence or absence of a marginal fasciole towards the 

 posterior of the test cannot be confirmed. Plastron plating, however, 

 is more decisive, in that the labral plate appears to be short and well 

 separated from the second sternal plate. For this reason we assign the 

 specimens to Cardiaster. 



Our specimens differs from the common Maastrichtian Cardiaster 

 granulosus (Goldfuss) in having a wider plastron with plates in each 

 column extending less far towards the opposite ambulacrum. It also 

 lacks enlarged primary tubercles running up the aboral surface of the 

 anterior interambulacra, which are characteristic of C. granulosus. 



Genus HEMIPNEUSTES L. Agassiz, 1836 



Diagnosis. Test cordate with flat base and domed upper surface. 

 Apical disc elongate with four gonopores; madrepores typically 

 extend over the anterior two genital plates. Paired ambulacra petaloid 

 with petal columns strongly unequal, the posterior column of pore- 

 pairs always being very much better developed. The anterior petals 

 are flexed strongly to the anterior. Frontal groove distinct from apex 

 to peristome, with sharp, but not keeled, margins. Periproct poste- 

 rior, with test indented immediately beneath periproct so that the 

 opening is just visible from below. Plastron composed of cuniform 

 alternating plates that extend almost across the full width of the 

 plastron. No fascicoles. 



PI. 7, figs 3, 4 



1778 Spatangus striato-radiatus Leske: 104, pi. 14, fig. A. 



1855 Holaster striato-radiatus d'Orbigny: 1 1 3, pis 802, 803. 



1875 Hemipneustes leymeriei Hebert: 594, pi. 20. 



1892 Hemipneustes leymeriei Hihe.rX,K\ck\hs: 110. 



Fig. 16 Camera lucida drawing of plating in Cardiaster sp. from the late 

 Ihanetian of Casas de Oraien (Navarra): BMNH EE6174. oral .surface. 

 Scale bar = 5 mm. 



