364 



BRACIIIOPODA OF THE 



same as the central muscles (which close the valves), and lateral anterior muscles, which 

 in Lingula enable the valves to move forward and backward on each other. No indica- 

 tions of transmedial or sliding muscles could be detected on any of the internal casts I have 

 been able to examine. As far as I could see, from the specimens placed at my disposal 

 for examination, the exterior surface of the valves was smooth and marked only by 

 concentric lines of growth. A large specimen measured 18 lines in length by 16 in 

 breadth; but I believe the species sometimes exceeded those dimensions. M. Caillard 

 mentions its presence at Sion, and M. de Tromelin observes that it is not rare in Brittany, 

 and that he found it also at Soulvache (Seine Inferieure). M. Barrois collected the 

 fossil at Chemire in Charnie. In the Albert Memorial Museum, at Exeter, may be 

 seen an internal cast showing both valves, the muscular impressions being sharply defined 

 on the surface corresponding to the ventral valve (Sup., PI. XL, fig. 21). We may also 

 state that occasionally we meet with a specimen so very much attenuated posteriorly as to 

 simulate Lingula crumena, an Upper-Llandovery species, as is exemplified by the figure, 

 Sup. PI. XL, fig. 27 : the specimen is in the Museum of Practical Geology. 



44. Lingula ? Salteri, Bav. 



Sil. Mom, PI. I, figs. 27—29 ; and B. S. Sup., PI. XL, 

 fig. 24. 



Lingula ? Salteri, Bav. Geol. Mag., new series, vol. vii, p. 342, pi. x, figs. 12, 13, 1880. 



The material afforded by the 

 that obtainable from the " Gres Armoricain 



Budleigh-Salterton 



pebbles is much inferior to 

 at Pontrean, in Brittany. One perfect 

 example in M. Lebesconte's collection measures 21 

 lines in length and breadth by 11 in depth, and 

 shows that the shell was nearly circular, or about as 

 broad as long, slightly indented or rounded in front. 

 Valves moderately convex ; a slight mesial longi- 

 tudinal depression or sinus dividing the dorsal valve 

 into two halves. The beak was of small projection, 

 and seemingly incurved at its extremity. The surface 

 of both valves, faintly and closely covered with fine 

 thread-like radiating striae, crossed at intervals by 

 concentric lines of growth. In an internal cast of a 



ventral valve the muscular impressions are sharply defined, and agree in character with 



those we observe in Lingula ? Haiokei. 



1. Internal cast of ventral valve, from 

 Pontrean, showing central mnscular im- 

 pression (a). 2. Profile of both valves. 



