FROM THE INFERIOR OOLITE. 501 



ear small ; posterior moderate, somewhat acute. Ears ornamented 

 with transverse markings. Surface with about twenty-two low, 

 distant, indistinct ribs, crossed by numerous raised, thread-like, 

 concentric threads, which are elevated by the ribs in the front part 

 of the shell, while on the hinder part two adjacent ones generally 

 unite on the top of each rib to form a larger and higher bar (fig. 13 a). 



One specimen in my collection from the Clypeus-Gait of Birdlip. 



Dimensions. Length 7 lines, width 6 lines. 



I am acquainted with no other Oolitic Pecten having a similar 

 ornamentation. 



Pecten l^eviradiattts, Waagen. 



1867. Pecten Icev iradiatus, Waagen in Benecke's geogn.-pal. Beitr. 

 vol. i. tab. 31. fig. 4. 



This is a flat circular shell with twenty or thirty distant, sharp, 

 triangular ribs, alternating in size, and with no other markings except 

 crowded microscopical concentric lineations, and sometimes a single 

 line of growth. 



The Jermyn-Street Museum possesses specimens of it from Brad- 

 ford Abbas, and I have collected it from Dundry, Mosterton, the 

 Oolitic sands of Bridport, and the Jurensis-zone of Yeovil Junction. 

 The original specimen was from the Soiveroyi-zone of Gingen, in 

 Wiirttemberg. Some small and rather more convex shells at Jermyn 

 Street, from " the bottom bed of sand X.E. of Cheltenham," may be 

 the young form of this species. In them the transverse markings 

 are rather more prominent and the flat valve is smooth. 



Pecten ptjellaris, n. sp. Plate XIX. figs. 3, 3 a. 



Shell small, orbicular, roundly convex, equilateral. Umbo large, 

 central, rounded, incurved, and extending above the hinge-line. 

 Ears small (the front one being rather the larger), obtuse, marked 

 with three flat rays and about fifteen raised rounded threads. Sur- 

 face covered by about twenty raised, rounded, narrow, and distant 

 smooth rays, half of which reach and curve over the umbo, and 

 half vanish in the grooves about three fourths of the way up. Grooves 

 concave, nearly twice the width of the rays, and crossed by very dis- 

 tant, fine, sharp threads, which are concave to the apex. Margin 

 circular, scalloped by the projection of the grooves. 



Size 5 lines long, by 5 broad, and 2 deep. 



The only specimen I have seen of this beautiful little shell is in 

 the British Museum, and comes from the Inferior Oolite near North- 

 ampton. From P. symmetricus, Morris, Hull's ' Geology of Chel- 

 tenham,' t. 1. fig. 3, it differs by the width of its grooves ; from 

 P. subspinosus, Schl., Goldf. Petr. Germ. t. 90. fig. 3 (specimens of 

 which from the Inferior Oolite of Brimscombe are in the Jermyn- 

 Street Museum), by the number of rays and absence of spines ; and 

 from P. anomalies, Terq. & Jour. Mem. Soc. Geol. Er. ser. 2, vol. ix. 

 1. 13. figs. 18-20, by its ungrouped costae. In neither of these species 

 are there any signs of the alternation of the rays, which would appear 

 to be very characteristic of the present shell. 



