CHONETES. 177 



small, rounded, ventral valves, with somewhat larger, scattered, blunt tubercles 

 or spinous markings. These seem to have been referred by Phillips l to his 

 P. laxispina, 2 but are included in this species by Davidson : St.productoides, Wen- 

 jukoff, 3 and St. calvus, Wenjukoff, 4 appear closely to correspond with them. It is 

 remarkable that amid the numerous specimens from the Pilton Beds nothing like 

 either of these two forms should have come under my notice, and I reserve for the 

 present my opinion as to their specific identity. 



3. Genus — Chonetes, Fischer de Waldheim, 1837. 

 1. Chonetes Hardrensis, Phillips, sp. ? Plate XXII, fig. 4. 



? 1841. Oethis Habdbensis, Phillips. Pal. Foss., p. 138, pi. lviii, figs. 101 a — d ; 



and pi. lx, fig. 104*. 

 ? 1855. Lept^na (Chonetes) Habdbensis, M'Coy. Brit. Pal. Foss., p. 454. 

 ? 1861. Chonetes Habdbensis, Davidson. Brit. Foss. Brach., vol. ii, p. 186, 



pi. xlvii, figs. 12—18,25?. 

 1865. — — — Ibid., vol. iii, p. 94, pi. xix, figs. 6— 9. 



? 1880. — Laquessiana, Davidson. Ibid., vol. iv, p. 312, pi. xxxiv, 



fig. 18. 

 1882. — Habdbensis, Davidson. Ibid., vol. v, p. 54, pi. iii, fig. 24. 



? 1884. — Laquessiana, Davidson. Ibid., vol. v, p. 280, pi. xx, figs. 



20—21 a. 



Description. — Ventral valve small, moderately transverse, suboval. Hinge-line 

 straight, as long as the width of the shell, bearing several obliquely-set spines. 

 Umbo small, incurved, not extending above the hinge. Contour very gently 

 convex. Front margin long, slightly convex. Side margins obliquely convex. 

 Lateral angles rather less than right angles. Surface covered with very numerous, 

 straight, divaricating rays, which are more or less nodulous. Dorsal valve concave ; 

 interior radially pitted. 



Size. — Length 6 mm., width 9 mm. 



Localities. — Top Orchard, Ashford Strand, Mainstone, Bradiford, Kingdon's 

 Shirwell, Croyde, Laticosta Cave, Baggy, Upcott Arch Quarry, Wrafton Lane, 

 Rock Hill Quarry, Ashhill Quarry. 



1 1841, Phillips, ' Pal. Foss.,' p. 59, pi. xxv, fig. 99. 



2 1861, Davidson, ' Brit. Foss. Brach.,' vol. ii, pt. 5, p. 166, pi. xxxiii, fig. 18 (under P. acu- 

 leatus). 



3 1886, Wenjukoff, 'Faun. Dev. Syst. Eussl.,' p. 45, pi. ii, figs. 5, 6. 

 * Ibid., p. 47, figs. 8—10. 



Z 



