498 



Dr. L. Hoysey — Coal-measure Arthropods. 



which, owing to their minuteness, or to the fact that they are 

 fragmentary, are not worthy of a separate and detailed description, 

 in the hope that their publication may inspire geologists to obtain 

 better and more perfect examples from other localities. 



The sources from which the following specimens were obtained 

 are: — Horizon, Top Hard Coal : Shipley Clay-pit, Derbyshire ; Brinsley 

 Clay-pit, near Eastwood, Nottinghamshire ; Digby Clay-pit, Kimberley, 

 Notts. Horizon between Waterloo and Ell Coals : Newthorpe Clay- 

 pit, Eastwood, Notts. Horizon, roof of Kilburn Coal : Trowell 

 Colliery refuse heap, Notts. 



Eig. 1, Leaia trigonioides, sp. nov. Several of these minute bodies, 

 about 3 mm. long, were discovered scattered throughout the substance 

 of an ironstone nodule from Shipley. They were for the most part 

 fragmentary, but two, one perfect and the other almost perfect but 

 crushed, have been selected for description. They represent the right 

 and left valves of what may betaken to be the carapace of ariiyllopod. 



PlG. 1. Leaia trigonioides, sp. nov. Eight and left valves of carapace. 

 Coal-measures : Shipley, near Ilkeston, Derbyshire. Nine times nat. size. 



The umbo is tumid, and is situated at the junction of the anterior and 

 middle third of the total length of the carapace. The hinge-line or dorsal 

 border is straight and terminates at the umbo. The anterior border runs 

 downwards and forwards, making a rounded angle whei'e it meets the 

 semicircular ventral border, which latter extends posteriorly to meet 

 the dorsal border in a more or less sharp angle. The surface of the 

 carapace is ornamented by two well-marked curved ridges, radiating 

 from the umbo ; one downwards and forwards, the other downwards 

 and backwards. These ridges die out before reaching the margin of 

 the valve, thus leaving a smooth flattened ventral border. The surface 

 is also ornamented with about nine concentric riblets, with smooth 

 bands between, which are best seen in the median area of the valve. 



A somewhat similar fossil was described by Lea 1 from Pennsylvania 

 under the name of Cypricardia leidyi. Professor T. Rupert Jones, 2 in his 

 monograph on the Phyllopods, gave it the name of Leaia leidyi, and 

 described two varieties, one Leaia leidyi, var. ivilliamsoniana, from 

 Ardwick near Manchester, and the other Leaia leidyi, var. salteriana, 

 from Cottage Row, Crail, Eifeshire. The present example agrees 

 fairly closely with the Eifeshire specimen; but, on the Avhole, it 

 seems best to create a new species for it, Leaia trigonioides, rather 

 than risk confusion by adding a varietal appellation. 



Eig. 2, Prestwiehia sp. This is mainly of interest owing to the 

 great difficulty of its interpretation, and was found at Shipley. It 



1 Proc. Acad. Nat. Sci. Philadelphia, vol. vii, p. 341, pi. iv, 1855. 



2 Mon. Paleeont. Soc, Appendix, p. 115, pi. i, figs. 21a, c, 1862. 



