OF CONCHOLOGY. 



115 



tion as not entitled to generic rank. It may be as well to re- 

 tain it for the group it indicates, in a subgeneric sense, as it is 



prior to Terehratella. 



? Suborenus Lyra. 



Lyra, Cumb., Sby. Min. Conch., 1816, {L. Meadii). 

 Terehrirostra, D'Orb., Pal. Fran. Cret. iv, p. 146, 1847. {T. 



lyra), Dav., Brit. Fos. Brach., p. 67. 

 Trigonosemiis, (part), Konig, [teste Dav.) 

 Waldkeimia, (part). Gray, Cat. Brach., p. 82. 



Shell having the back of the neural valve very long, almost 

 straight, with a false area and narrow deltidium ; divided length- 

 wise internally by the dental plates ; truncated and perforate 

 at the extremity. Loop unknown. 



Type Lyra lleadii, Cumberland. Foss. Cretaceous. 



D'Orbigny, Davidson and Woodward seem inclined to place 

 this subgenus under Terehratella, as having the loop attached to 

 the septum ; while Gray places it as a section of Waldkeimia. 

 This group had also better be retained for the same reasons 

 given in regard to Trigonosemus. 



Subgenus Terebratella, D'Orb. 



Terehratella, D'Orb., Pal. Fran. Ter. Cret., vol. iv, p. 110, 



1847. Dav. Int. Brit. Brach., p. Qb, (T. dorsata). 

 ? ? Deltliyridcea, McCoy, Syn. Carb. Foss. Ir., p. 1-30, 1844, 



fig. 2r. 



Delthyris, Menke, (not Dalman or v. Buch,) Syn., ed. ii, p. 

 96, {D. dorsata, Lam.), 1830. 



Shell with a moderate beak on the neural valve ; usually 

 truncate and somewhat recurved, fixed by a peduncle passing 

 through the foramen. The latter is usually incomplete and the 

 deltidia consequently separated. An indistinct ridge or septum 

 sometimes exists in the neural valve. 



Brachia composed of two lateral loops, the posterior limbs of 

 which meet behind the mouth and the anterior before it. The 

 central spiral lobe is obsolete or entirely absent. 



This section contains the typical forms of the genus and al- 

 most all the recent species. The fossil representatives range 

 from the Cretaceous upwards. 



The diagnosis of Beltliyridcea, as far as external characters go, 

 would well agree with such species as T. caurina, but according 

 to Mr. Davidson no type was given by Prof. McCoy, and his 

 figure is unrecognizable. Dr. Gray gives T. peetiniformis as 



