OF COXCHOLOGY. 161 



the cardinal border, recalling to some extent the teeth of this 

 form ; though from the examination of the casts of Trimerella 

 in the cabinet of Prof. James Hall, and gutta percha moulds 

 prepared from them by Mr. Whitfield, it is evident that they 

 have few characters in common with the one now under con- 

 sideration. As Dr. Lindstrom did not give his species any name, 

 and lam unable to find any other reference to it, I would pro- 

 pose the provisional name of Gotlandia Lindstromi. 



This genus was unknown before the publication of Lindstrom's 

 paper, and it proves to be extremely interesting. Here is a 

 shell whose nearest affinities are vfhh Linc/ula and Obolus, which, 

 nevertheless, is as distinctly articulated as Terebratula itself ! 

 This raises the query as to the comparative value of the char- 

 acters used by Gray, ^. e., the spiral or non spiral brachia, with 

 those used by most naturalists in separating the Bi-aehiopoda 

 into orders. The muscular impressions would seem to have been 

 remarkably posterior and the tubes may have been the seat of 

 the ovaria. 



Genus LINGULEPIS, Hall. 

 Lingulepis, Hall, 16th Regents Rep. 1863, p. 129. 



Shell linguloid, iuequivalve, equilateral, oval-ovate or spatu- 

 late ; in the neural valve the visceral area is tripartite, the late- 

 ral extensions the larger ; in the haemal valve the area is flabel- 

 liform. Shell corneous, phosphatic. 



The scars of the anterior adductors appear to be in the sinuses 

 on each sid.e of the median prolongation of the visceral area in 

 the neural valve. The posterior occlusers are very small, and 

 placed within the visceral area much as in Lingula, except that 

 they are close together, and located further back. The anterior 

 occlusors median; before the mesial point of the area? 



Type. L. pinnceformis, Hall, 16th Regent's Rep. pi. vi, fig. 

 15, 16. Owen, Geol. Minn, and Wise. p. 582, pi. I. B. 

 fig. 3, 4, 8. 



Fossil in the Silurian formation. 



This form is closely related to Lingula ; the visceral area is 

 slightly thickened, so that it leaves an indentation on internal 

 casts. These have been referred to as muscular impressions. 



Section OBOLINiE. 



Post adductor scars more or less separated from the median 

 line. 



