Mr. T. R. Jones on Scandinavian Beyrichise. 89 



in No. 2. limestone, and two in No. 3.) ; and from their friable 

 condition the carapace appears to have been of an unusually de- 

 licate structure. 



This rare and interesting species is named after Prof. M'Coy, 

 who founded the genus and devoted much labour to the eluci- 

 dation of the species of this and other allied forms of palseozoic 

 Entomostraca. 



5. Beyrichia Salteriana, nov. sp. PL V. figs. 15, 16. 



Valves narrow oblong ; caudal portion wider than the cephalic ; 

 marginal rim of the anterior, inferior, and posterior borders uni- 

 form, well developed, and impressed with a series of shallow 

 pits along the ventral portion. Surface finely punctate ; divided 

 into three unequal subtriangular convexities or lobes, separated 

 by a very narrow forked or Y-shaped furrow. The posterior 

 lobe is the largest ; and the middle one, which is slightly in 

 advance of the centre of the valve and is pushed up to the dorsal 

 border, is the smallest. 



This species offers a strong contrast to B. Buchiana in the 

 width of the surface-lobes and the narrowness of the furrows ; 

 and it could scarcely answer to the name of ^'jugosa '\ or ridged, 

 were it not that its system of furrows is equivalent to that of 

 B, tuherculata, which is at the opposite extremity of this group. 



This small, but elegant and well-characterized species is nu- 

 merous in No. 5. limestone ; and I dedicate it with much plea- 

 sure to my friend Mr. Salter, Palaeontologist of the Geological 

 Survey, to whom we are indebted for much information on the 

 history of the Entomostraca of the Silurian rocks. 



(Corrugate.) 



6. Beyrichia iVilckensiana, nov. sp. PI. V. figs. 17, 18. 



Carapace-valves contracted anteriorly, almost reniform. Sur- 

 face of valve smooth, highly convex, divided into three unequal 

 lobes by two short furrows, the anterior of which is near the 

 centre of the valve. The middle lobe, lying between the fur- 

 rows, is rounded, prominent, projecting over the dorsal edge, 

 and passes, by a narrow and sometimes constricted neck, into 

 the convex body of the valve with which the front and hind 

 lobes are continuous. The middle lobe, though prominent, is 

 the smallest, and the anterior lobe is the widest, but depressed. 

 The ventral part of the convex surface, where the lobes unite, 

 hangs over the narrow flat rim of the inferior margin of the 

 valve, and is separated from it by a deep wrinkle, which dies out 



