On the Palceozoic Bivalved Entomostraca. 391 



side of the tail, nearly halfway between the tip of the latter 

 and the body. 



millim. 



Total length 45 



Body 14 



From eud of snout to eye 5 



Tail 32 



Height of tail 14 



XLVIII. — Notes on the Palceozoio Bivalved Entomostraca. — 

 No. XVIII. Some Species of the Eutomididse. By Prof. 

 T. RurERT Jones, F.R.S., F.G.S. 



[Plate XV. *] 



The genus Entomis, first determined in 1861, was described 

 in detail in the Ann. & Mag. Nat. Hist. ser. 4, 1873, vol. xi. 

 p. 413. E. tuheo-osa, Jones, mentioned op. cit. pp. 413 and 

 415, is not very uncommon in some Up per- Silurian strata 

 and deserves further notice. Its carapace- valves themselves 

 have been very rarely preserved f ; but the casts afford some 

 material for further illustration.. 



1. Entomis tuberosa, Jones. (PI. XV. fig. 1.) 



Ento7nis tuberosa, Jones, Mem. Geol. Surv. Scot!., Explau. Map 32, 1861, 



p. 137, pi. ii. lig. 5 ; Ann. & Mag. Nat. Hist. ser. 4, 1873, vol. xi. 



p. 413. 

 Entomis pelagica, Barrande, Syst. Sil. Boheme, vol. i. Suppl. 1872, 



p. 515, pi. xxxiv. figs. 1-6 ; De Kouincli, Mem. Soc. roy. iSci. Liege, 



ser. 2, vol. vi. 1876, p. 45. 

 Entomis tuberosa, Woodward, Cat. Brit. Foss. Crust. 1877, p. 120. 

 Entomis pelayica et E. tuberosa, R. Eth., Jun., Cat. Austral. Fossils, 



1878, p. 16. 



Valves suboval, in a specimen (fig. 1) from tlie Pentland 

 Hills, Scotland |, jy inch long and i\ v.ide, and one from 

 Bow Bridge, Ludlow §, ^ inch long and ^ wide. Although 

 the pressure which has affected the mudstone matrix of 

 these casts has more or less altered the shape of the valves, 



* The drawing of this lithogTaphic plate has been made imder a grant 

 from the Royal Society. 



t Henry Johnson, Esq., F.G.S. , of Dudley, has kindly lent me a weU- 

 preserved specimen, with the test, while this paper is going through the 

 press. 



X Cat. Cambr. Silur. Foss. Mus. Pract. Geol. 1878, p. 130 (i|), in a 

 yellowish sandstone, with two small spiral Gasteropoda. 



§ Loc. cit. (If), in grey calcareous shale. 



30* 



