170 



erior half of the valve. The valves are evenly rounded, and highest about 

 the middle. An ocular tubercle, or traces of one, can usually be seen in 

 the upper anterior region of the valve. 



Specie Length of the known species, 3 to 6 min. 



referred to it. 



Range. Through the Etcheminian and Protolenus Faunas. 



Besides the species described below the foil owing appear to. belong here : 

 Priuiitia pyriformis. f ) Both of the 



P. (?) fusiformis. * ) Protolenus Fauna. 



Aparchites (?) robustus f also of that fauna comes near this group. 



Distinguished This genus is seemingly different from Nothozoe of Barrande. Nothozoe 

 genera. i s an ov&l fossil occurring in the Ordovician of Bohemia, which the above 



author has referred doubtfully to the Ostracoda. The size, however, is 

 much greater than that of the fossils we are dealing with herejand no 

 ocular tubercle has been recognized. For these reasons, as well as on 

 account of the obscurity of the characters of Nothozoe, it seenis inadvi- 

 sable to use this name for the Etcheminian species described below. 



Equal objections may be taken to the referring of the Cape Breton 

 species in question to the genus Primitia, or to Aparchites, which hitherto 

 the author has used for the Lower Cambrian forms. The species of these 

 genera are small, and the absence of an ocular tubercle in one, and the 

 presence of a median sulcus in the other, are further distinctions from 

 the species which the author has referred to Indiana. Few species of the 

 genera Primit.ia and Aparchites attain a size in which the area of the 

 valve is a tenth that of the shells referred to this genus. 



INDIANA OVALIS. P'. XIII, fig. 8 a to c. 



Can. Rec. Sci., Montreal, 1902, p. 461. 



Indiana This species is ovate, broader behind than in front. Hinge line about 



one half of the length of the valve. Cardinal curves of moderate length. 

 Anterior marginal curve long, arched ; posterior short, more strongly 

 arched. No marginal furrows seen. Ocular tubercle close to the hinge 

 line ; a narrow diagonal furrow behind the eye, extends to the lower end 

 of the anterior marginal curve. 



Sculpture. Along the lower margin are fine anastomosing ridges ; the 

 decorticated part of the valve shows the lower margin of a semi-circular 

 muscle scar, directly behind the ocular tubercle, neav the hinge line. 



t Roy. Soc. Can. Trans., vol. iv, sec. iv, p. 132, pi. i. fig. 3 a to c 1 and 4 to c. 

 * N.Y. Acad. Sci., Trans., vol. xiv, p. 237, pi. vii, figs. 3 a and b. 

 t Individuals of Nothozoe pollens ( -'yst. Silur. Bohm. vol. i, Supp. p. 536 have an area 

 of valve 70 times greater than the largest species of Indiana. 



