Palceozoic Bivalved Entomostraca. 351 



(Ann. & Mag. Nat. Hist. Sept. 1855, vol. xvi. p. 16(3, pi. vi. 

 fig. 9). The hinder lobe is not divided nor constricted; but 

 with age both the hind and front lobe generally bear one or 

 more tubercles on their prominent dorsal ends. This is the 

 "granulated variety^' referred to in the Geol. Mag. 1881, 

 pp. 345 and 346. The older individuals in some cases pass into 

 var, tuherculata^ Salter. 



The front lobe is greatly enlarged ventraliy in some speci- 

 mens. This condition occurs in individuals of several distinct 

 species (Upper- Silurian, see above, p. 342) as well as 

 varieties ; and therefore it is not a specific character, as Boll 

 thought it was when he described and named a form similar to 

 the above as B. 'protuherans. What organ of the animal took 

 on an increased structure, so as to cause the valves to be thus 

 locally swollen in the antero- ventral region, we do not know. 

 The ovaries in living Ostracoda and Limnadiads are situated 

 in the postero-dorsal region (see above, p. 340). 



B. Kloedeni-granulafa, Smith Coll. no. 9i, 2, 5, from Dudley 

 Castle ; no. 10, railway- cutting, side of the Severn, Iron- 

 brido-e; no. 21, railway-cutting, Coalbrook Dale. All with 

 the " big lobe." 



Vine Coll. LXVI9, from the Tickwood Beds ; XXXIX, 

 passing into var. tuherculataj Salter, from bed no. 46. All 

 big-lobed. 



(2) BeyricMa Klcedeni^ var. nuda, Jones. 



This is the B. KJcedeni with a " smooth valve," referred to 

 in the Geol. Mag. 1881, p. 345 ; see also Ann. & Mag. Nat., 

 Hist. Sept. 1855, vol. xvi. p. 166, pi. vi. fig. 7. A smooth 

 variety of the typical B. Klcedeni^ but larger than the figured 

 specimen above alluded to, and with the exaggerated antero- 

 ventral lobe, occurred in Mr. G. R. Vine's collection, from the 

 Wenlock Shales, no. 46, but has been lost. In Mr. J. Smith's 

 collection (no. 24 slide) is a large smooth B. Klcedeni^ or, at 

 least, one with the granulation reduced to a minimum. This 

 is from the Wren's Nest, Dudley. In Mr. Vine's collection 

 (slide no. LXVi) is a large B. Klcedeni, quite smooth, from 

 the Tickwood Beds. 



The large individuals of each variety put on strong mar- 

 ginal edges and exaggerate their lobes dorsal ly into apical 

 bosses or projecting tips. 



(3) BeyricMa Klcedeni^ var. antiquata, Jones. 



Beyrichia Klcedeni, var. antiqunta, Jones, Ann. & Mag. Nat. Hist. 

 Sept. 1855, vol. xvi. p. 167, pi. vi.fior. 8. 



24* 



