SPIRIFERIDtE. 



139 



I am by no means convinced that Prof. Hall is correct in considering the Terehra- 

 tula ? lepida of Goldfuss to be a type of his genus, and we know that another exceedingly 

 compressed shell, Atrypa {OrtJiis) lens, Philhps [T. dividua, Schnurr), was possessed of spiral 

 appendages (see Schnurr's work on the Devonian Brachiopoda of the Eifel, pi. xxiv, 

 fig. 2) ; and, indeed, as stated by Prof. Hall himself, the internal characters of his genus 

 have been determined mainly from the interior of L.flabellites; and, consequently, until 

 a further investigation into the interior dispositions of the other mentioned types has been 

 effected, I would not venture to adopt as conclusive the generic identification proposed for 

 our Silurian shell. 



Position and Locality. This shell appears to be characteristic of the Upper, and 

 to be more rarely found in the Lower Llandovery beds : it is exceedingly abundant in 

 certain localities. In the " Silurian System " it is mentioned from Ankerdine Hill, 

 Abberley district ; Worcester Beacon, Malvern. I have seen it from May Hill and 

 Huntley Hill, in the May Hill district. It covers large surfaces at Charfield Green, 

 and Damory Hill, Michaelswood-Chace, Gloucestershire ; Tortworth ; Merrick Wood, 

 near Much Wenlock ; and Wooltack Bay in the Marloes district. 



In addition to these localities, in the 3rd vol. of the ' Memoirs of the Geological 

 Survey,' Prof. Ramsay and Mr. Salter mention Llandeilo, Llangadock, Builth, Presteign, 

 Longmynd, Church Stretton, Norbury, Chirbury, and Malvern, in the Upper Llandovery 

 rocks. 



In Scotland it is exceedingly plentiful in rocks of the Llandovery age, at Saugh HiU ; 

 Lower Thrave, and Braes, in sandstone ; at Ardmillan in a blue limestone, &c., all in the 

 Girvan district, Ayrshire, 



For Ireland Prof. M'Coy mentions the following localities : — In calcareous shales at 

 Ardaun, Cong, Co. Galway. Very common in the sandstone of Blackwater Bridge, 

 Leenane ; Boocaun, Cong ; Cappacorcogue, Cong ; Glencraff ; Kilbride, &c., all in the 

 County of Galway, and in Upper or Lower Llandovery rocks. 



In America Prof. Hall states it to be very abundant in the upper green shale 



crystalline matter was first deposited upon these internal organs, which have subsequently almost entirely 

 decomposed, leaving in the cavities fragments of the substance showing the original form of the crura 

 and appendages. 



" The shells of this form have been described as Terebratula, and more recently have been included 

 with Rhynchonella, from which they differ conspicuously in the great inequality of the valves and the 

 extension of the hinge-line, as well as in their internal structure. I have, therefore, referred to this genus 

 the Leptocoelia {Atrypa) disparilis of the Niagara group, the Terebratula lepida of Goldfuss. The T. sub- 

 lepida and T. Duboisii of Murchison, de Vern., and de Keyserling (Geol. of Russia and the Ural Mountains). 

 The L. concava and L. imbricata, in the Lower Helderberg group, are analogous forms which have been 

 referred to this species. 



" The Atrypa hemisphcerica of Murchison is apparently a characteristic form of this genus, as well as 

 A. planoconvexa, both from the Clinton group. The internal structure, however, has been determined 

 from the species of the Oriskany Sandstone and Lower Helderberg specimens, but mainly from the 

 former." 



