DEVONIAN FAUNA. 



Class— CRUSTACEA, Lamarck. 



Sub-class— MALACOSTRAC A, Latreille, 1806. 



Order— PHYLLOCARIDA, Packard, 1879. 



1. Genus — Echinocaeis, Whitfield, 1880.^ 



1. Echinocaeis Whidbornei, Jones and Woodward, PI. I, fig. 3. 



1889. Echinocaeis Whidbohnei, Jones and Woodward. Geo!. Mag., dec. 3, 



vol. vi, p. 385, pi. xi, fig. 1. 



Description. — Carapace bivalved. Each valve subcircular. Dorsal margin 

 straight, about three-quarters the length ; front margin slightly curved ; ventral 

 and posterior margins much curved. Margins (except the dorsal) bounded by a 

 sharp triangular elevated rim. Surface irregularly convex, divided into three 

 groups of swellings, which are approximately arranged as follows. — A line drawn 

 from the postero-dorsal to the antero -ventral point, and another from nearly the 

 antero-dorsal to the central point, represent furrows or deep concavities dividing 

 the test into three compartments, which we may call the dorsal, the anterior, and the 

 posterior compartments. The dorsal compartment is again divided by shallower 

 grooves into a long narrow hinder swelling, abroad central, and a minute anterior 

 swelling. The anterior compartment is indistinctly divided into a small anterior 

 swelling occupying the extreme antero-superior corner of the test, a large diffuse 

 pyriform swelling, and a minute hinder swelling occupying the posterior angle of 

 the compartment. The posterior compartment has one large diffuse swelling filling 

 it entirely, except its anterior part, which contains a narrow fusiform swelling or 

 promontory starting from the centre, and corresponding to the rear swelling of the 

 dorsal compartment. These swellings are each, except the posterior, ornamented 

 by one or more scattered sharp little tubercles. Two slightly curved longitudinal 

 ridges divide the posterior compartment into three nearly equal petaloid areas, 

 which are transversely slightly concave. These ridges and the rim (at least in the 

 posterior dorsal region) bear a single regular row of similar sharp tubercles. 



Size. — Left valve 9*2 mm. long by 7*4 mm. high. 



Locality. — A single specimen, found by Mr. Dufton in a quarry near Sloly, close 

 to the third milestone on the Barnstaple and Ilfracombe Road in the shales of the 



^ 1888. Hall and Clarke, ' Pal. N. Y.,' vol. vii, pp. 168—181, pis. xxviii— xxx. 



