CONTRIBUTIONS TO PALEONTOLOGY. 129 



Orthis, like 0. ohlata and O. vanuxemi. The muscular impression 

 in the spatulate valve is narrow above, gradually widening in the 

 middle, with a central line; while its lower part is divided into 

 three lobes, the central one shorter, the lateral ones longer, and 

 diverging so that the outer margins of the impression are nearly 

 parallel to the margin of the shell. The central longitudinal line 

 seems to have been made by an extremely thin septum, which 

 does not reach to the lower extremity of the central muscular 

 impression. 



Although several specimens of the broader and shorter form 

 have been exfolig.ted so as to show the muscular impression, they 

 are all of the- same character, and I am compelled to infer that 

 they are of the same valve. At the same time, three individuals 

 of the spatulate form (which have been exfoliated with much dif- 

 fficulty) ail presented an identical form of muscular impression. 



Notwithstanding that these fossils have all the external cha- 

 racteristics of LiNGULA, from which it would be very undesirable 

 to separate them, were it possible to do otherwise, yet the form 

 of muscular impressions is so unlike that of modern Lingul^, as 

 well as of those in the Devonian rocks which I have seen, that it 

 becomes necessary to propose some other designation. In order 

 to retain some indication of their relations, I propose the name 



LiNGULEPIS. 



GENUS LINGULEPIS ( n. g.). 



Shells linguloid, inequivalve, equilateral, oval-ovate or spatulate : 

 muscular impression, in one valve, flabelliform ; in the other, 

 tripartite, the lateral divisions larger. Shell corneous, phospha- 

 tic. 

 The characters above described are from specimens of apparently opposite 



valves, from the St. Croix falls : their relations are not positively known, 



no entire specimens having been obtained. 



LINGULEPIS PINNAFOKMIS. 



( LINGULA PINNAFORMIS (Owen).) 



PLATE VI, FIGS. 14 A 16; AND ? FIGS. 12, 13 & 15. 

 Lingula pinnaformis ; Owen, G'eol. Report of "Wisconsin, Iowa and Minnesota, pa. 583, 



,yryK PI. IB, f.4,6§. V ..O 2k 



: Idem, Reports of Wisconsin, Vol. i, p. 21, f. 3, and p. 435. \^U"V 



Shell spatulate, upper part attenuate, acute, slightly truncate at 

 the apex; convex in the middle, with the sides, towards the 

 [Senate, No. 115.] 17 



