136 TRANSACTIONS OF THE [MaR. 17, 
BEYRICHONA ROTUNDATA, n. sp. Pl. vii., fig. 9. 
Broadly semi-circular. Flattened area of the valve extending 
halfway across from the hinge-line; valve more elevated in front 
than behind, having a narrow and obscure marginal fold behind, 
but none visible on the front half. 
Sculpture. Surface as in B. planata. 
Size. Length 5 mm.; height 3} mm. 
Horizon and locality. Shales of Assise 2 at Hanford Brook. 
Scarce. 
Compare this species with Walcott’s Aristozoe rotundata from 
the Lower Cambrian of Washington county, N.Y. The general 
form is similar, but it differs in the narrower marginal fold and 
smaller size. 
APARCHITES, T. Rupert Jones. 
APARCHITES SECUNDA, n. sp. Pl. vii., figs. 11 @ and b. 
Oval, tumid, hinge-line more than half of the length of the 
valve; near the anterior end is a slight swelling where the eye- 
spot might be; there is a faint thread-like ridge along the car- 
dinal line, where the margin of the valve is straight; the ventral 
border is rolled in on each side and no marginal fold is visible. 
Sculpture. *The surface is minutely rugose. 
Size. Length 4 mm.; width 24 mm. 
Horizon and locality. Sandstones of the upper part of Assise 
3, at Hanford Brook. 
PRIMITIA, T. Rupert Jones. 
PRIMITIA AURORA PI. viii., figs. 1 a@ to e. 
Trans. Roy. Soc. Can., vol. xi., p. 98, pl. xvii., fig. 5 a to c. 
This species was found in the dark gray sandstones of Assise 
1, some years ago. 
PRIMITIA OCULATA, n. sp. PI. viii., figs. 2 a and b. 
Obliquely oval, tumid, straight on the hinge-line, which is 
about two-thirds of the length of the valve; there is a promi- 
nent ocular tubercle near the anterior end, and behind the tuber- 
cle a shallow groove. Two depressions are noticeable on the 
posterior end of the value. ‘ 
Sculpture. The test is distinctly pitted. 
Size. Length 3 mm.; height 2 mm. 
Horizon and locality. Sandstones of the upper part of Assise 
3. Rare. 
