Bivalve Shells of Nova Scotia. 125 



would either seem to have been less gregarious in its habits, 

 or to be represented by mere stragglers from its proper 

 locality. It may therefore, be not unreasonably regarded 

 as a distinct species. Most of the specimens in our collec- 

 tions are from the South Joggins, but there are some from 

 Cape Breton. Compare N. triangularis, Sby. 



3. Naiadites mytiloides, s. n. 

 5 



Fig. 5. — Naiadites mytiloides, s. n., Chimney Corner, Cape 

 Breton, enlarged x 2. 



This small and pretty species has more the aspect of 

 modern mytili than the others, but its internal markings 

 are unknown. It is narrow in front, with the hinge-line 

 slightly curved and the shell widening to the rounded 

 posterior end, where it is regularly curved. The ventral 

 margin is slightly incurved and flattened in the best pre- 

 served specimens ; but most of the specimens are more or 

 less crushed. The epidermis is not preserved, and the sur- 

 face shows only a few concentric growth -lines. 



These shells occur abundantly, but for the most part 

 broken or crushed, in shale from the coal-formation of 

 Chimney Corner, Cape Breton, collected by a former student 

 of McGill, Mr. Keighswander. They are nearly uniform in 

 size, about half an inch in length. This shell is from one of 

 the more northern parts of the Cape Breton coal-fields. It 

 may be compared with Myalina meliniformis, M. & W. from 

 Illinois, also with N. Garinata, Sby., England. 

 Genus anthracomya, Salter. 



Shell transverse ; slightly inequivalve ? inequilateral, the 

 anterior end being small and rounded, the posterior end 

 rounded and wider. Umbones usually near the anterior 

 end. Hinge-line straight without teeth ; ligament external ; 

 indications of a byssal furrow in front in some species ; sur- 

 face marked with concentric lamellae and ridges of growth. 



