OF CONCHOLOGY. 105 



The type of this species is not to be found, and I am unable 

 to suggest its proper place from Dr. Gould's description, Suess 

 (1. c.) refers it to Megerlea. Ilab., Hakodadi Bay, Japan. 



Terehratula cubensis, Pourt., Bull. Mus. Comp. Zoo). No. 7, p. 

 109. W. Indies. 



Genus RENSSEL Ji:RIA, Hall. 



Atrypa, Conrad, Ann. Rep. Geol. of New York, 1839, p. 45. 



Pentavierus, Vanuxem, Journ. Phil. Ac. Nat. Sci. viii, p. 266, 

 .1843. 



Bleganteris, Hall, An. Rep. Reg. Univ. N. Y. Pal. Foss, 

 1857. 



Mensselceria, Hall, 12th An. Rep. Reg. Univ. N. Y. p. 39, Oct. 

 1859. 



Shell punctate, inequivalve ; neural valve with a prominent 

 apex ; foramen complete or incomplete, terminal, sometimes con- 

 cealed. Teeth supported by receding plates, which are attached 

 in the cavity of the apex of the neural valve ; septum present. 



Haemal valve with a more or less prominent hinge plate and 

 cardinal process. The hinge plate is perforated near the apex 

 of the valve, forming a communication with the cavity of the 

 umbo. 



Two moderately stout processes are given out from the hinge 

 upon which the crura are attached at a strong angle, projecting 

 above and below, and at the lower extremity giving oft" the main 

 branches of the apophyses about at a right angle. The latter 

 are produced anteriorly, meeting, and forming a sharp point 

 connected by a thin plate of shelly matter, at the posterior edge 

 of which, in the median line, a slender process is projected up- 

 ward, nearly parallel with the crura, toward the neural valve. 



Type. Mensselceria ovoides, Hall = Tei'ebratula ovoides, 

 Eaton, Geol. Textb. 1832, p. 45. 



Fossil in the Lower and Upper Helderberg and Oriskany beds 

 of New York. 



Prof. Hall has aptly compared a view of the apophyses with 

 the tongue of a bird having the hyoid bones attached. 



Genus TEREBRATULINA, D'Orb. 

 TerebratuUna, D'Orb., Comptes Rendus xxv, p. 268, 1847. 



Shell with the foramen incomplete and deltidiura usually rudi- 

 mentary. Crura united at their tips in the adult, forming a more 

 or less sinuous ring. 



Brachia as in Terebratula. 



