CARBONIFEROUS LIMESTONE BRACIIIOPODA. 249 



derate, obtuse, lateral angulation nearly obsolete; perforation 

 large ; surface closely granulo-punctate under the lens; dental 

 lamelloe at sides of foramen large, diverging at 45°. Length 

 1 inch 6 lines, proportional length of entering valve y^^^^, 

 width -^Q^Q, depth of receiving valve y%%, depth of entering 

 valve y%%. 



The broad-ovate, tumid form distinguishes this easily from 

 the other carboniferous species, as well as the absence of any 

 distinct mesial hollow or emargination of the front in either 

 valve. The punctures of the surface are considerably smaller 

 than those of the S. virgoides (M'Coy) or S. hastata. 



Rare in the carboniferous limestone of Derbyshire. 



{Col. University of Cambridge.) 



Spirifera fasciculata (M'Coy). 



Desc. Longitudinally very broad-ovate ; length and width nearly 

 equal, depressed; hinge-line only half the width of the shell; 

 cardinal area rather more than one-third higher than wide ; 

 lateral margins horizontal, front margin abruptly raised into 

 a defined, obtusely angular sinus; entering valve depressed 

 slightly, and gently convex on the sides; mesial fold very 

 strongly defined by a sulcus and depression of the surface on 

 each side ; convex, very obtusely angular, but not very promi- 

 nent, having three ridges near the beak, which dichotomize 

 into six as they approach the margin ; each side has about 

 seven to nine flat, smooth ridges near the beak, most of which 

 branch into two or three as they approach the edge ; the in- 

 tervening sulci very narrow; receiving valve more convex, 

 moderately gibbous along the middle, sloping rapidly towards 

 the side margins ; mesial hollow strongly defined, very deep, 

 narrow, flattened near the beak, widening, and receiving about 

 two plaits on each side of the middle one as it reaches the front 

 sinus. Width of average-sized specimen 9 lines, proportional 

 length of receiving valve -f^Q, of entering valve -^-q-q, width of 

 cardinal area ^^^^j, width of sinus in front margin -^-^^q, depth 

 of ditto -j^Q^Q, depth of entering valve y^^j, of receivmg valve 

 tVo i width of very large Irish specimen 1 inch 5 lines, pro- 

 portional length of receiving valve y^^^^, depth of both valves 



50 

 TOTJ- 



Distinguished from the S. duplicicosta (Phill.) by the more 

 longitudinally oval, depressed form, very short hinge-line and 

 cardinal area. 



Not very uncommon in the carboniferous limestone of Derby- 

 shire. 



[Col. University of Cambridge.) 



