the Palaeozoic Bivalved Entomostraca. 



227 



projection of the marginal rim, and by being turned inwards 

 for a considerable depth. Its extreme edge has for most of its 

 length a delicate raised rim, which, however, passes outwards 

 and backwards to join the great marginal ridge, where the 

 latter projects as a thick, sharp-edged crest along the posterior 

 edge of the valve. Somewhat analogous features may be 

 traced in Primitia cristata, J. & H., Ann. Nat. Hist. ser. 3. 

 vol. xvi. pi. 13. fig. 1. 



The dorsal border of Moorea silurica is . indented along its 

 marginal ridge, so as to form with its fellow, if similarly con- 

 structed, a narrow elliptical depression at the back, along the 

 hinge-line, as in P. cristata above alluded to. 



Our specimens were found in a band of micaceous lime- 

 stone in the Upper Ludlow rocks, with Kirkbya fibula, at 

 Hales End, Malvern, where it was not uncommon. 



Table of Measurements in thousandths of an inch. 



Name. 



Reference. 



Length. 



Height. 



Thick- 

 ness. 



Cythere corbuloides, sp.n 



Grindrodiana, sp.n 



Bairdia Phillipsiana, sp.n 



Thlipsura corpulenta, sp.n 



tuberosa, sp.n 



V-scripta, sp.n 



Cytherellina siliqua, var. grandis, not: 



(ordinary variety) 



, var. tersa 



var. ovata 



siliqua, Jones, sp. (ordinary var.) 



„ (another specimen) 



iEchmina cuspidata, sp. n 



clavulus, sp.n 



Beyrichia intermedia, sp. n 



Primitia lenticularis, sp. n 



umbilicata, J.tylf. 



bipunctata, Salter 



excavata, sp. «.§ 



Kirkbya fibula, sp. «.§ 



Moorea silurica, sp. w.§ 



PI. XV. f. 4, p. 211 



woodcut, f. 1, p. 212 



PLXlV.f. 7, p. 213 



PL XV. f. 1, p. 214 



„ f. 2, p. 214 



„ f. 3, p. 214 



PL XIV. f.l, p. 217 



„ f. 2, p. 217 



„ f. 3, p. 217 



* f- 4, p. 217 



„ f. 6, p. 217 



„ f. 5, p. 217 



PL XIV. f. 8, & 



woodcut,f.2,p.218 



„ f. 3, p. 218 



PL XV. f. 7, p. 218 



woodcut, f. 4, p. 219 



PL XV. f. 6, p. 220 



woodcut, f. 5, p. 220 



PL XV. f. 10, p. 222 



„ f. 9, p. 224 



„ f. 8, p. 226 



41 



24t 



53 



50 



43 



32 



83 



53 



33 



70 



53 



46 



58 



47 

 22 

 44 

 37 

 50 

 33 

 32 

 38 



32* 



11 



33J 



30 



23 



20 



42 



24 



17 



45 



24 



20 



33 



38 

 17 

 33 

 27 

 37 

 25 

 20 

 27 



35 

 10? 

 26 

 33 

 19 

 16 

 39 

 26 

 16 

 40 

 ? 



? 

 '? 

 24 



? 



? 

 22 

 14 

 24 



* Large valve. 



t Another specimen, found lately, measures -r-JHhr inch in length, and 

 -i-§4t7 in height. 



% Smaller valve, -rf-g-^ inch. 



§ The thickness in the last three species is obtained by doubling the 

 thickness of the single valve. 



