168 DEVONIAN FAUNA. 



compare this form with (Ehlert's figures of 0. hipponyx, which lies between it 

 and 0. umbraculum. 



3. Genus — Strophomena, de Blainville, 1825, 

 1. Strophomena rhomboidalis, Wilckens, sp. Plate XX, fig. 5. 



1865. Steophomena bhomboidalis, var. analoga, Davidson. Brit. Foss. Brach., 



vol. iii, p. 76, pi. xv, figs. 15 — 17. 

 1884. — — Davidson. Ibid., vol. v, p. 467. 



1893. — — var. analoga, Whidborne. Dev. Fauna, 



vol. ii, p. 149. 



Localities. — This is a moderately common shell in the Pilton Beds, and is 

 represented in most museums. Among the localities are Top Orchard, Pilton, 

 Braunton, Goodleigh Road, Croyde, Poleshill, Pottington, Fremington, Upcott 

 Arch Quarry, Wrafton Lane. It is also found in the Ilfracombe Beds. 



Remarks. — Our specimens are often excellently preserved, and include the 

 interiors of both valves as well as the exterior. I can see nothing to distinguish 

 them as a variety ; if anything, they are more like the Silurian than the 

 Carboniferous shells. Davidson, in fact, adopted for the typical Silurian form the 

 description he had before given for his Carboniferous variety, and he ultimately 

 dropped the varietal name analoga from the Devonian and Carboniferous shells. 

 Our North Devon specimens certainly support this view. 



V. Family — Productid2B, King, 1846. 

 1. Genus — Productds, Sowerby, 1812. 

 1. Prodtjctus PR.SLONGUS, Sowerby, sp. Plate XX, figs. 12, 12 a, 13, 13 a. 



1840. Leptjena pb-ELonga, Sowerby. Geol. Trans., ser. 2, vol. v, pt. 3, pi. liii, 



fig. 29. 

 1855. Peoducta pb^longa, M'Coy. Brit. Pal. Foss., p. 390. 

 1865. Pbodtjctus pe^ilongus, Davidson. Brit. Foss. Brach., vol. iii, p. 102, 



pi. xix, figs. 22—25. 



Description. — Ventral valve very elongate, suboval, evenly convex. Hinge- 

 line nearly, if not quite, as long as the width of the shell. Umbo extremely 

 large, extending very greatly beyond the hinge, and recurved upon it so that its 

 apex is in its close proximity. Surface with a very narrow, shallow, irregular, 



