86 
an obsure mesial elevation in front, corresponding with the sinus of the ventral valve; the 
beak incurved, and buried beneath that of the ventral valve. Surface with numerous very 
delicate concentric lines of growth, which become crowded together and conspicuous towards 
the front margin. 
This species is somewhat variable in shape ; some specimens have their greatest width a 
little in front of the middle of the shell; but others {and these are perhaps “the commonest ) 
have the greatest width at about two- thirds of the distance from the beak, or even nearer the 
front than this, the shell thus assuming a sub-triangular form. Average specimens have a 
length of six lines, a width of five lines, and a depth ‘of about three lines, 
In the most perfect specimens I have seen, the foramen is large and conspicuous, and is 
perforated in the summit of the beak of the ventral valve, so as to look upwards, 
Locality and Formation.—Rare in the Corniferous Limestone of Port Colborne. Hamil- 
ton formation of Widder. 
104. SPIRIGERA scITULA (Hall). 
Atrypa scitula (Hall), Report on the Fourth Geol. Dist. New York, p. 171, Fig. 1. 
Athyris (?) scitula (Billings), Canadian Journal, New Series, Vol. V., p. 27 8, ‘Figs. 35, 
36 (cet. eaclusis). 
Meristella scitula (Hall), Pal. New York, Vol. IV., Plate XLVIL., Figs. 34-38. 
Shell ovate, both valves convex, the ventral valve the most SO, somewhat compressed to- 
wards the front. Ventral valve with a prominent beak, which is ‘ineurved over that of the 
dorsal valye, and is perforated by a conspicuous foramen. Dorsal valve most convex above 
the middle, depressed towards the front, with a small beak, which is buried beneath that of 
the dorsal valve. Surface marked by fine concentric strie. Length of an average example one 
inch ; width, nine lines ; depth, six lines. 
I have only one well preserved example of this species, and am therefore, not prepared 
tojdiscuss its affinities. Hall’s species certainly seems to me to be identical in part with that 
figured by Mr. Billings. The Charionella circe of Mr. Billings appears to me to be quite dis- 
tinct, though it is asserted by Hall to be identical with his Meristella scitula. 
Locality y and Formation.-—Rare in the Corniferous Limestone of Port Colborne. 
Genus ATHYRIS (McCoy). 
Shell variable in shape, the valves unequally convex, with or without a mesial sinus end 
fold, articulated by teeth and sockets. Beak of the ventral valve incurved, usually overly.ug 
and in contact with the beak of the dorsal valve, not perforated by a foramen, or with the 
foramen concealed when fully grown. ‘In the interior of larger or ventral valve the dental 
plates are fixed to and along the sides of a longitudinal prominence or convex arch-shaped 
plate, which extends to less than a third of the length of the shell, with its narrow end fitting 
into the extremity of the beak, and its lateral diverging edges to the bottom of the valve. 
: The interior of the smaller or dorsal valve is partly divided by a large, deep 
longitudinal septum, which extends from the extremity of the umbo to about two. thirds of 
the Jeneth of the shell, supporting at its origin the hinge-plate, which is divided into two por- 
tions by a narrow oradually widening channel ; to the socket ridges are affixed the spiral cones, 
the extremities of which are directed towards the lateral margin of the shell; on either side 
of the septum are seen two muscular scars formed by the adductor” (Davidson, British Fossil 
Brachiopoda, General Introduction, p. 85.) 
Accepting the above definition of the genus Athyris, there are only two forms which have 
come under my notice in the Devonian Rocks of Ontario, which appear to be referable to this 
genus, and the position of one of these somewhat doubtful, The forms in question are A thyris 
nasuta (Conrad sp. = A. clara, Billings), and A. Maia (Billings), of which the last is referred 
by Hall to the genus Spirifera. 
105. Atnyris NASUTA (Conrad). 
Atrypa nasuta (Conrad), Ann. Report on the Paleontology of New York, p. 18. 
Meristella nasuta (Hall), Thirteenth Report on the State Cabinet, p. 93. 
Meristella elissa (Hall), Fourteenth Report on the State Cabinet, p. 100. 
