IIU PALEONTOLOGY OF NEW YORK. 



Genus S I P H N T R E T A , de Verneuil. 1845. 



PLATE IV, FIGS. •24-26, 37, 3S. 



1S29. Crania, Eicuwald. Zoologia specialis, vol. i, p. 274. 



1840. rtrf6ra/!i/a, Eicuwald. Uebei- das siliiriscli.^Schichten-Syst. von Esthlaml; Journ. Nat. Heil- 



kund. ined.-chii-urg-. Acad. St. Petersb., p. 138. 

 1S42. Terebratula, Eiohwald. Die Urwelt Russlands, Heft 2, p. 145. 

 1S4.T Siphojwtreta, dk Vkrneuil. In Murchison, de Verneuil and Keyserling's Geol. de la Russie 



d'Eurojie et des mont. de I'Oural, p. 286, pi. i, figs. 13, 14. 



1848. Siphonotrda (parti'm),KvTon{i!i.. Ueber die BrachiopOden-Familie der Siphonotretasae ; Vei-- 



handl. i-uss.-kais. mineral. Gesellsch. zu St. Petersburg, p. 261, pis. 

 vi, vii. 



1849. Siplionotreta, Morki.s. AniuaLs of Natural History, Ser. 2, vol. iv, p. 315. 



1853. Siplimwtreta, DaviD.son. Introd. British Fossil Brachiopoda, p. 131, pi. ix, tigs. 261-270 (not 268). 



1866. Siplionotreta. Davidson. British Silurian Briichiopoda, p. 75, pi viii, figs. 1-6. 



1871. Siphonotreta (partim), yuENSTEOT. Petrefaktenkunde Deutschlands; Brachiopoden, p.(>74, pl.lil. 



1877. Siphonotreta, Davidson. Geological Magazine, p. 18. 



1883. Siplionotreta, Davidso.v. British Siluiian Brachiopoda, Suppl., p. 217, pi. xvi, hg.«. 31-33. 



Diagnosis. Sliell elongate-oval, inequivalve ; valves iiiarticulated. Pedicle- 

 vralve the more convex, with a straight, elevated, conical, and perforated beak, 

 the circular foramen opening at the apex and communicating with the interior 

 of the .shell by a tubular canal, which narrows slightly as it passes inward. No 

 cardinal area or deltidium is present, the growth-lines passing between the beak 

 and the posterior margin as elsewhere on the shell. Brachial valve depressed- 

 convex; beak marginal; posterior margin regularly arched and thickened. 

 Interior of pedicle-valve with muscular impressions confined to the umbonal 

 region. Close alongside the opening of the sipho, just within the cardinal 

 margin, lie two elongate scars which are accompanied on either side by broader, 

 somewhat expanded or tlabellate, simple and less distinct impressions. Directly 

 in front of the middle pair lies a small central scar, in the axis of the shell, 

 and at either side of it a transversely elongate impression. These latter im- 

 pressions are distinctly separated from the former by a transverse ridge. 



In the brachial valve the impressions are ecpially concentrated, the entire 

 muscular area being bounded on its posterior margin by a prominent ridge 

 which, at the sides, merges into a compound lateral scar. The central portion 

 of the area is nmch depres.sed and is divided axially by a narrow ridge or 

 septum. 



