LATE CRETACEOUS-EARLY TERTIARY ECHINOIDS 



b 



Fig. 39 Camera lucida drawings of plating in Ovidaster reticulatus sp. 

 nov. from the Maastrichtian black shale facies at Sarasate (Navarra); 

 holotype BMNH EE6074. a, apical surface; b, oral surface; c, lateral; d, 

 posterior. Interambulacra shaded. Scale bar = 5 mm. 



Fig. 40 Camera lucida drawings of plating in Ovulaster reticulatus sp. 

 nov. from the Maastrichtian black shale facies at Sarasate, (Navarra); 

 paratype BMNH EE6236. a, apical surface; b, apical disc. Scale bars: a 

 = 5 mm; b = 1 mm. 



ILinthia sp. Fig. 41 



Occurrence. Upper Thanetian, P. pseudomenardii Zone. Casas de 

 Oraien, Navarra Province, Spain. 



Material studied. MGB 37436. 



Remarks. A single specimen showing the characteristic large 

 plastron and very short, wide labral plate of a. Linthia (Fig. 41 ). The 

 upper surface is damaged, but shows a rather wide anterior groove 



131 



and the anterior parts of two sunken petals. Impressions in the 

 infilling sediment suggest that the posterior petals were only about 

 half the length of the anterior pair. 



Family AEROPSIDAE Lambert, 1 896 

 Genus SPHENASTER Jeffery, gen. nov. 



Type species. Sphemister larumbensis Jeffery, sp. nov. 



Etymology. From sphenos - a wedge. 



Diagnosis. Narrow wedge-shaped test. Broad shallowly sunken 

 unpaired ambulacrum with enlarged pore-pairs. Short, flush, non- 

 petaloid paired ambulacra. Ethmophract apical disc with two 

 gonopores. Peripetalous fasciole passes immediately behind the 

 apical system and below the ambitus anteriorly. Enlarged tubercles 

 are developed along the edges of the unpaired ambulacrum. 



Remarks. The new genus is most similar to Aeropsis, from which 

 differs in having a wedge-shaped (rather than cylindrical) test with 

 an obliquely truncated posterior, a less anterior apical system and a 

 number of enlarged tubercles on the apical surface. Aceste differs in 

 having an ethmolytic apical system, a deeply sunken frontal groove 

 leading to the mouth, single pores in the paired ambulacra and 

 uniform tuberculation. Sphenaster is flat across the anterior margin, 

 has pore-pairs in all ambulacra and, although damaged, appears to 

 have no vestibule leading into its mouth. 



Sphenaster larumbensis Jeffery, sp. nov. 



PI. 11, figs 8-12; Fig. 42 



Etymology. Larumbe - the locality at which the specimen was 

 found. 



Holotype. Holotype and only known specimen BMNH EE6073. 



Occurrence. Lower Thanetian, upper part of Coraster Beds, 

 Larumbe, Navarra Province, Spain. 



Description. The holotype measures 14.6 mm in length and 8.4 

 mm in width (58% of test length). In horizontal outline, the test 

 describes an elongate pentagon. It is flat across the anterior margin, 

 broadens to the widest point (approximately two thirds of test length 

 from the anterior margin) and narrows to the rounded posterior. 

 Maximum height is 10.3 mm (7 1 % of test length), midway along the 

 test. In profile, the test is wedge-shaped, sloping gently to the 

 anterior from the apical system and with a somewhat gibbous lower 

 surface. The posterior is oblique with a very slight subanal heel. 



The paired ambulacra are flush and non-petaloid with tiny, incon- 

 spicuous pore-pairs. By contrast, the unpaired ambulacrum is broad 

 and slightly sunken and contains enlarged pore-pairs. Pore-pairs are 

 obliquely positioned and diminish in size towards the anterior mar- 

 gin of the test. 



The plastron is amphistemous with a long narrow labral plate 

 followed by two equally long, narrow sternal plates. The suture 

 between these plates runs along the midline of the test. 



The apical system is positioned 39% of test length from the 

 anterior margin. It has two large genital plates each with a gonopore, 

 and five small ocular plates. A small number of hydropores are 

 present on the madreporite. Plating cannot be clearly made out, but 

 it appears to be ethmophract in structure. 



The peristome is circular or rounded pentagonal with no rim. It 

 measures 1.7 mm in diameter (20% of maximum test width) and is 

 situated 21% of test length from the anterior margin. Although the 



