44 SUPPLEMENT TO GREAT OOLITE MOLLUSCA. 



CUCULL^A CLATHRATA, Leclc. Tab. XXXIX, figs. 4, 4 a. 



CLATHRATA, Leckenby. Journ. Geol. Soc., 1858, vol. xv, pi. 3, fig. 4. 



Testa subrhomboidali injlata, umbonibus antemedianis magnis, valde separates, area 

 amp/a, excavata, lanceolata, basi subrecto ; valvis ruyis lont/itudinalibus, irregularibus, 

 lineisque radiantibus, crebris tenuibus, dorso angulo obtuso et obliquo. 



Shell subrhomboidal, inflated ; umbones large, placed anterior to the middle of the 

 valves, separated by a large lanceolate area ; there is an oblique obtuse angle upon the 

 posterior side, separating a concave posterior space from the middle portion of the valves ; 

 the surface has large, longitudinal, irregular, rugose plications crossed by closely arranged, 

 delicate, radiating lines; the lower border is nearly straight, and slightly sinuated. 



The shorter posterior side and larger umbones distinguish it from Area lata, Dunker, 

 to which in other respects it has a considerable resemblance. 



Dimensions. Length, 26 lines; height, 14 lines; diameter through both the valves, 

 16 lines ; space separating the points of the umbones, 3 lines. 



Geological Position and Locality. The Cornbrash of Scarborough, also in the 

 Kelloway Rock of the same locality. In the collection of Mr. Leckenby. 



NUCULA MENKEI, Roem. Tab. XXXIX, fig. 2. 



NOCULA MENKEI, Roemer. Nordd. Ool., t. 6, fig. 10, p. 98. 



Testa ovata, media ventricosa concentrice striata, antice brevissima acuta oblique 

 truncata, cordato-subexcavata, posterius producta rotundata, basi subarcuata, umbonibus 

 crassis incurvis, aream lanceolatam hand efformantibus. (Roemer.) 



Shell ovate, anterior side very short, somewhat excavated, and pointed at its lower 

 extremity ; posterior border lengthened, curved, sloping obliquely downwards, its lower 

 extremity rounded, base slightly curved elliptically, umbones large, incurved, area very 

 slightly defined ; the middle portion of the valves is moderately convex, with a few distant 

 plications of growth, and delicate concentric striations obscurely defined. 



Nucula variabilis, Sow., approximates to this species, but is without the anterior 

 excavation, and has a more lengthened posterior side. Nucula nuclens, Desl., is shorter 

 and more globose. 



Geological Positions and Localities. Roemer records Nucula Menkei in the Portland 

 Limestone of Wendhausen. Mr. Whiteaves has collected it in the Great Oolite of Kirk- 

 lington, and in the Corabrash of Islip, Oxon. 



