. The Canadian naturalist and quarterly journal of science. Natural history -- Periodicals. 424 THE CANADIAN NATURALIST. [DeC. horny bivalve shell, with one valve, the dorsal, smaller than the other, the beak of which projects and has a notch (foramen) below, through which passes a stalk or pedicel for attachment. The interior of the shell is lined with the two valves of the mantle, and is occupied principally with the two-fringed and ciliated arms coiled like cork-screws. (Fig. 94.) At the base Fig. 94. a. Rhynchonella psittacea. Interior of dorsal valve, showing (a) adductor muscles, and (6)
. The Canadian naturalist and quarterly journal of science. Natural history -- Periodicals. 424 THE CANADIAN NATURALIST. [DeC. horny bivalve shell, with one valve, the dorsal, smaller than the other, the beak of which projects and has a notch (foramen) below, through which passes a stalk or pedicel for attachment. The interior of the shell is lined with the two valves of the mantle, and is occupied principally with the two-fringed and ciliated arms coiled like cork-screws. (Fig. 94.) At the base Fig. 94. a. Rhynchonella psittacea. Interior of dorsal valve, showing (a) adductor muscles, and (6) spiral arms; drawn from a specimen dredged at Gaspe— natural size. of these is the mouth, leading to a small stomach and short in- testine. It has a more complicated nervous and circulating system than those of the Tunicates, and has several pairs of muscles placed near the hinge for opening and closing the shell and regulating the movements of the creature on its pedicel. The Rhynchonella is found attached to stones and dead shells in moderately deep water. In addition to this species, we have on our coasts Terehratulina septentrionalis, of more elongated form than the above-named species, ribbed longitudinally, with a round perforation at the beak, instead of a notch, and with an internal shelly loop. Other species found on our coasts are Waldheimia cranium, and Tert- hratella Spitzhergensis, a northern form found in Labrador, and also fossil in the post-pliocene clay of Riviere du Loup. Wald- heimia cranium has as yet been found only on the coast of Nova Scotia, by Willis. It has been ascertained that the young of some Brachiopods much resemble Polyzoa in form and structure. (Morse). Though recent Brachiopods are few in species, vast numbers are found fossil. Mr. Billings's catalogues include nearly 100 species, from the lower Silurian alone, in Canada; and Dr. Bigsby, in his Thesaurus Siluricus, enumerates 429 species from the Silurian of America, whereas leps than 100 l
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