124 



BRITISH SILURIAN BRACHIOPODA. 



we have figured in an internal cast of the same valve of AtUyris ambigua ('Monogr. 

 Carbonif. Brach.,' PI. XVII, fig. 14). It is, however, with considerable hesitation that 

 I group this shell with Athyris, as we are still too little acquainted with its internal 

 arrangements, and M'Coy and Salter may be correct in placing it with Bhynclmiella. 

 It varies also considerably in depth, some specimens being much depressed, while others 

 are more or less gibbous. 



Lindstrom informs me that his Swedish Spirigerina cordata will require to be placed 

 among the synonyms of the shell under description ; the Gothland specimens that I have 

 seen are, however, in the cast, more strongly striated than our own. 



Position and Locality. The shell occurs plentifully in the Wenlock shale of Stump's 

 Wood, and in the Woolhope limestone, on the road between Affrick and Crew's Hill, 

 Malvern ; also at Delves Green, near Walsall. Prof. M'Coy has noted it as being abun- 

 dant in the Bala limestone ; but this is erroneous, the young shell of a Lower Silurian 

 Orthis being the form referred to (Salter). 



On the Continent it has been found in the island of Gothland. 



Genus — Retzia, Kiny. 

 Bef. King, ' Monograph of Permian Fossils,' p. 137, 1850. 



Generic Char. Prof. King describes his genus as " a Spiriferida in general oval longi- 

 tudinally, ribbed or striated, with large punctures ; large valve foraminated at or near the 

 apex of the umbone, with a triangular area and closed fissure. Type, Terebratula 

 Adrieni (De Verneuil). This interesting genus, well distinguished by the above cha- 

 racters from other Spiriferidcs, embraces some pretty species, such as Betzia Baylei 

 {Terebratula, Davidson), B. Bouchardii {Terebratula, Dav.), B. Oliviani {Terebratula, 

 Vern.), and B. Salteri {Terebratula, Dav.). Terebratula ferita and some other Spirigerous 

 Terebratulaeform species," &c. King, therefore, takes as the type of his genus 

 Betzia Adrieni, a Spanish Devonian shell, described and figured by de Verneuil in the 

 ' Bull. Soc. G^ol. Prance,' 2nd series, vol. i, pi. xiv, fig. II ; and by myself in PI. VI 

 of my " General Introduction." B. Oliviani is also a Spanish Devonian shell, figured 

 Ukewise in the same French plate above mentioned ; but none of these shells, nor the 

 others above alluded to, possess " a triangular area and closed fissure." Betzia Adrieni 

 is longitudinally oval, costated, with the beak truncated by a small circular foramen, 

 partly margined by a deltidium in two pieces. 



In an interesting article on the genus Betzia, published in the * Sixteenth Report of 

 the Regents of the University of the State Cabinet of New York,' p. 53, 1863, Prof. J. 

 Hall remarks that, in regard to the entire character and limitations of this genus, there 

 still exist some doubt and difierencc of opinion amongst palaeontologists, and that he has 

 consequently considered it desirable to propose a different arrangement of the species 

 formerly grouped in the genus Betzia; that for such shells as B. serpentina {Terebratula, 



