Palceozoic Bivalved Entomostraca. 409 



XI. ^CHMiNA, Jones & Holl, 1869. 

 (Ann. & Mag. Nat. Hist. ser. 4, vol. iii. p. 217.) 



1. ^chmina hovina^ Jones. (PI. XXII. fig. 8.) 



ALchmina bovma, Jones, Ann. & Mag. Nat. Hist. ser. 6, vol. xix. p. 412, 

 pi. xiii. fig. 0. 



Some drawings sent from Stockholm, and of one of which 

 fig. 8 is a copy, show a form identical with the British species 

 from the Wenlock Shale, but more delicately toothed along 

 the free margin. It is common in the shale of Frojel, Goth- 

 land, also belonging to the Wenlock series. 



XII. BuESULELLA *, Jones, 1887. 



(Silur. Ostrac. GothlaDd, 1887, p. 7.) 



This is a small, bivalved, probably Ostracodal form, with 

 more or less triangular valves, which have one or two horn- 

 like projections on the ventral edge of each valve. 



1. Bursulella triangularis^ Jones. (PI. XXII. figs. 5, 6.) 



Bursulella triangularis, Jones, Silur. Ostrac. Gothland, 1887, p. 7, 

 woodcuts. 



The upper and lower edges of the valves are straight, but 

 the ventral edge is much shorter than the other, and a delicate 

 spike projects from each of its angles. The corners of each 

 valve are somewhat rounded and on the lower edge are 

 marked inside with a series of shallow pits, making a slightly 

 crenate contact-line. In outline this curious bivalve, which 

 is probably auOstracod, looks like a little subtriangular^jwrse 

 (hence the generic name), widest at the top, and ornamented 

 below with two neat little projections. 



It occurs in the Cephalopodan Limestone of Samsugn, in 

 Othem, and the uppermost beds of Slite, some twenty speci- 

 mens having been found. 



2. Bursulella semiluna, Jones. 

 (PI. XXII. figs. 4 a, 4 6, 4 c.) 



Bursulella seiniluna, Jones, Silur. Ostrac. Gothland, 1887, p. 7. 



Here the valves have a nearly semicircular ventral outline 



* Bursa, a pursn ; bursula, a little purse ; bursulella, a very little purse. 



