28 BULLETIN OF THE 
growth, a moderate distance apart, and distinct. The interior cast of the 
dorsal valve is in general moderately convex, at the edges being more finely 
and less distinctly striate than the exterior surface. The margin along the 
beak is flat. The cardinal scars in the cast follow the outline of the shell, and 
are well defined along their exterior outline, but not along their interior. The 
reverse is true of the casts of the lateral scars. The lateral scars unite with 
the central scars, forming a figure comparable with that of a reversed W, 
which is distinctly outlined along the outline facing away from the beak, but 
is indistinct along the outline facing the cardinal scars. The diameter of the 
shell is 5 mm. 
Locality and position. — Station No. 2, North Attleborough, Mass., Cam- 
brian, one specimen. 
3. Fordilla (Troyensis, Barrande?). 
Plate I. Fig. 4. 
Cast of left valve 7mm. long and 4mm. broad, moderately convex along the 
border, quite strongly convex near the hinge line. The broadest part of the 
shell is slightly anterior to the middle of the length of the shell. Posteriorly 
the shell decreases rapidly in breadth. The posterior extremity is rounded, 
but more attenuate than in specimens figured by Walcott. Anteriorly the 
border of the cast is narrowly indented; in consequence of the indentation, 
the border is produced as a small lobe, and forms the anterior extremity of the 
shell. A rather broad, shallow groove runs along the shell near the margin. 
The cast shows no striz. 
Compared with typical specimens of this species, the North Attleborough form 
is larger, more attenuate posteriorly, and more strongly arched near the hinge 
line. Walcott, in his Second Contribution to Cambrian Faunas,* figures, on 
Plate XI. fig. 3 b, a cast which forms a connecting link between the form 
here described and the typical forms, which have a broader posterior outline. 
Locality and position. — Station No. 1, North Attleborough, Mass., Cambrian, 
one specimen; also at Troy and Schodack Landing, N. Y. 
4. Lamellibranch ? 
Plate I. Fig. 5. 
A single specimen of entirely unknown relations has at least the general 
outline of a Lamellibranch. It is 9.5mm. long and 3.7mm. wide. The 
border is gently curved; the hinge line almost straight. Along the hinge line 
is a flat, strongly inclined narrow field, with fine strie almost perpendicular 
to the hinge line. The rest of the shell forms a surface almost perpendicular 
to the hinge area. It is finely striated, the curved strie following the outline 
of the border. The broadest part of the shell is about one third the dis- 
* Bulletin U. S. Geol. Survey, No. 80. 
