. The Canadian naturalist and geologist. Natural history -- Periodicals. Fig. 1. Fig. 2. IFlg. 3. In the Brachiopoda, such as the Lingula, Orthis, Spirifer, Leptena, Strophomena, and others, there are two valves, and it has been ascertained by the dissection of specimens of those species at present living in the oceans, that one of these valves is placed upon the back and the other on the ventral side of the animal. Hence they are called dorsal and ventral valves. Fie, 1 shews the ventral valve of Orthis tricenaria, a Trenton Limestone sj^ecies, very abundant in that rock at the lower end of t
. The Canadian naturalist and geologist. Natural history -- Periodicals. Fig. 1. Fig. 2. IFlg. 3. In the Brachiopoda, such as the Lingula, Orthis, Spirifer, Leptena, Strophomena, and others, there are two valves, and it has been ascertained by the dissection of specimens of those species at present living in the oceans, that one of these valves is placed upon the back and the other on the ventral side of the animal. Hence they are called dorsal and ventral valves. Fie, 1 shews the ventral valve of Orthis tricenaria, a Trenton Limestone sj^ecies, very abundant in that rock at the lower end of the Allumette Island on the Ottawa. Fig. 2 is a dorsal view of the same specimen; in this figure it will be observed that the dorsal valve is shorter than the other. It extends only to the straight line across the figure near the top. The broad triangular space above the line is a portion of the ventral valve. Fig. 3 is a side view of a specimen shewing how the ventral valve projects above the other in a sharp hook-like termination, which is called the beak. Both valves have a beak, but that of the ventral is almost always the largest, and projects the highest. The hinge line is simply the hinge portion of the shells. Fig. 4. Fig. 5. Fig. 4 is an end view of Orthis tricenaria looking at the hinge, the ventral valve being uppermost. The valves are each terminated by a flat space, as if they had been cut off with a knife. These constitute what is called the " cardinal areci)' "â hinge area,^ or simply " the area.'' The area in the genus Orthis is penetrated in the centre by an angular aperture, shewn in fig. 4, by the lozenge-shaped black space in the centre. this aperture it is supposed the pedicle passed, by which the animal was attached to the bottom of the sea. It is called the ''foramen,'' or "; It consists of a triangular notch in each valve, deepest in the ventral valvCi 9. Please note that these images are extracted from scanned
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