11 BRITISH CARBONIFEROUS BRACHIOPODA. 



beak is rather more incurved than in T. hastata proper. Dimensions from two examples 

 have produced — 



Length 17^, width 15, depth 10 lines (type). 

 „ 22^, „ 16, „ 12 lines. 

 Loc. Derbyshire, the Isle of Man, &c. 



Terebratula sacculus, Martin, Sp. Plate I, figs. 23, 24, 27, 29, 30. 



Conchyliolithus anomites (sacculus), Martin. Petref. Derbesiana, tab. xlvi, figs. 1 



and 2, 1809. 

 Terebratula sacculus, J. de C. Sow. Min. Con., tab. 446, fig. 1, Jan. 1824. 



— — Fleming. Brit. Animals, p. 371, 1828. 



— — Phillips. Geol. York., vol. ii, p. 222; pi. xii, fig. 2, 1836. 



— hastata (part), Be Koninck. Animaux Fossiles de la Belgique, p. 294; 



pi. xx, fig. 3 c, d, e,f, g, h, I; not a, b, 1843. 



— sacculus, M'Coy. Carb. Foss. of Ireland, p. 156, 1844 ; and British 



Palaeozoic Fossils, p. 411, 1855. 



Spec. Char. Obovate, or somewhat obscurely pentagonal, notched and emarginated 

 in front ; surface smooth, marked only by a few lines of growth ; valves nearly equally 

 deep, and more or less inflated ; dorsal valve regularly convex, or with a slight depression 

 near the front. The ventral valve presents a rather deep and concave mesial furrow, 

 commencing at about half the length of the valve, and extending to the front. The 

 margin of the ventral valve is straight in front, or indents by a convex curve the corre- 

 sponding portion of the opposite one ; the beak and foramen are of moderate dimensions, 

 incurved with obscurely marked ridges ; shell-structure punctuated. Dimensions variable. 



Length 14, width 11, depth 7 lines 



,, 8, „ 6, „ 4 lines (Martin's type). 



Obs. Martin states that " the form of the shell is purse-like, its margin blunt, hol- 

 lowed out opposite the beak by an obtuse indentation, which is sometimes continued along 

 the back of the beaked valve, in the form of a slight hollow furrow or wave." 1 The last- 

 named character is that which generally distinguishes it best from T. hastata and T. 

 vesicularis ; but, although this peculiar sinus is well and deeply marked in many 

 individuals, it is at times but obscurely so in others, and which occurrence has, no doubt, 

 tempted some authors to unite both Sowerby's and Martin's shell under a single denomi- 



1 In p. 14, of the Systematic Arrangement of the Petrifactions of Martin's species, described in the 

 Fetrifacta Derbiensis,' the author again alludes to his Anomia sacculus as follows : 



Sacculus. 24. Conch. Anomites subscrotiformis lsevis, margine obtuso : sinu exsculpto. 



Tab. xlvi, figs. 1, 2. 

 or. v. Sinu a margine ad valvulse perforatae dorsum ducto. 

 h. v. Sinu subobsoleto. Tab. xlvi, figs. 1, 2. 



