36 LOWER CAMBRIAN FOSSILS — WALCOTT. 



me to consider that they are all of animal origin, and that many of the 

 so-called species were formed by one species of animal. Also, that 

 specific differences in the animals making tbem would not generally be 

 shown iu the casts of the burrows and trails. 



In a paper on the genus Cruziana and allied forms I will give my 

 reasons for considering them burrows and trails of animals, and not 

 the casts of fucoids. 



Kutorgina labradorica var. swantonensis var. now 



A comparison of a series of specimens of K. labradorica, from New- 

 foundland, with a series from near S wanton, Vermont, shows constant dif- 

 ferences. The stria? on the Swautou shells are finer and more regular, 

 and the valves are less transverse in proportion to the length, and the 

 beak of the ventral valve is less elevated. 



Formation and locality. — Lower Cambiau. East of Swantou and 

 Highgate Springs, Vermont. 



Nat. Mus. Cat. Invt. Foss., No. 15329. 



Obolella atlantica sp. nov. 



This is a small species of Obolella that occurs iu great abundance in 

 Newfoundland and also (less frequently) at North Attleborough, Massa- 

 chusetts * It is of the type of Obolella crassa, but differs in the details 

 of the interior surface and the average smaller size. 



Localities.— Manuel's Brook, Topsail and Brigus Heads, Conception 

 Bay, Newfoundland. 



Nat. Mus. Cat. Invt, Foss,, No. 18322. 



Camerella minor sp. uov. 



Shell small, moderately convex ; valves about equal in depth. Ven- 

 tral valve convex on the umbo, with the beak slightly incurved ; cardi- 

 nal slopes nearly straight from the beak to the rounded sides; the 

 posterior or umbonal third of the valve is usually more or less tumid, 

 a ridge of growth separating it from the anterior portion of the shell. 

 Dorsal valve shorter than the ventral valve; transversely oval, most 

 prominent at the umbo ; beak very small and terminating at the cardi- 

 nal margin. 



The casts of the surface show only concentric lines of growth. 

 Usually a marked line or ridge separates the tumid umbonal portion of 

 the shell from the anterior part. 



The casts of the interior of the ventral valve have a small pit just in 

 front of the termination of the beak, from which two narrow depres- 

 sions extend forward and separate off a short, narrow, central ridge 



* Bull. Mus. Comp. Zool., Harvard College, vol. 16,1888; Prelim. Descpt. North 

 Attleborough Fossils, p. 27. 



