127 



valve, and two arched lateral impressions at the side of the valve are 

 probably due to the vascular trunks. 



Sculpture. The valves in this species have a dull surface, which under 

 the lens is resolved into irregular beaded ridges, concentric to the umbo, 

 but often these ridges sink down, leaving a granular, or irregularly 

 beaded surface. 



Size. Length of the ventral 14 mm. width 11 mm. The dorsal valve 

 is 2 to 3 mm. shorter than the ventral ; depth of the two valves together 

 about 3 mm. 



Horizon and locality. In the gray shale of Assise E. 1 d. ; also a few 

 valves in E. 1 b. and E. 1. c. Lower Etcheminian, Dugald brook, Esca- 

 sonie, N. S. 



This species has a long acuminate beak to the ventral valve like Lin- Compared 

 gulepis pinniformis, but the dorsal valve is different from the dorsal of species. 

 that species ; its central group of scars is advanced far to the front as in 

 Eoobolus, and in connection with this, a flattened band traverses the cen- 

 tre of this valve, the flattened area is narrower than that of Michwitzia 

 monilifera and Obohts major and it is a smaller species than the latter. 



This species is like L. acutangulus Roem* of the Upper Cambrian- of 

 .Texas, but is larger and differs in the more acuminate apex of the ven- 

 tral valve, and in having the central muscle scars parallel to the long dia- 

 meter of the valve. In the dorsal valve also the prints of the central 

 muscles are much farther forward on the valve, and those of the poste- 

 rior laterals farther apart. 



Lingulepis Gregwa is a thin shell. In the species from Assise E. 1 c. 

 only a thin chitinous layer is preserved, some moulds have not even that. 

 No ventral valves were found in this assise. 



In the Assise E. 1 d. at Boundary brook, the ventral, although ac- 

 cuminate, is blunted at the end, and the pedicle groove inside, rises 

 gradually from the visceral cavity, without the ledge or shoulder often 

 seen at the back of the shell in other species. 



The above description covers the more salient characters of L. Gregwa, 

 but larger collections made in 1901, enable me to add some particulars. 



In the majority of individuals the sides of the ventral valve are 

 straighter toward the beak, and the point is not so acuminate as repre- 

 sentedin the figures (la and 6). Also the back part of the dorsal valve is 

 more prolonged than as represented in the figures (1 d and ?) ; so that there 

 is -not usually such a discrepancy between the length of the valves as 3 mm. 



* Proc. Nat. Mus, U. S., vol. xxi p. 392, pi. xxvii, fig. 6 and pi. xxvii, fig. 1 and 2. 



