. Appendix to the Manual of Mollusca of Woodward, : containing such recent and fossil shells as are not mentioned in the second edition of that work . the socket-walls, and run parallelwith the inner margin of the valve. The spiral cones are connected byan entire and continuous loop, whichis confined to the rostral part of theshell. The loop arises from the posteriorportion of the first volutions of thespires, and curves gently forwardand upward ; the central or elevatedportion is situated between and be-hind the cones, and forms a more orless abrupt curve, or is prolongedinto a po
. Appendix to the Manual of Mollusca of Woodward, : containing such recent and fossil shells as are not mentioned in the second edition of that work . the socket-walls, and run parallelwith the inner margin of the valve. The spiral cones are connected byan entire and continuous loop, whichis confined to the rostral part of theshell. The loop arises from the posteriorportion of the first volutions of thespires, and curves gently forwardand upward ; the central or elevatedportion is situated between and be-hind the cones, and forms a more orless abrupt curve, or is prolongedinto a point directed towards thedorsal valve. The existence and form of this loop have beenascertained in several different varieties of A. reticularis, aswell as in A. spinosa, Hall.—(Whitfield.)Sub-genus, Zygospipa, Hall, 1862. Synonym, Stenocisrna, Conrad, 1847. Spiral cones connectedby an entire and continuous loop in a very similar manner tothat shown to exist in Atrypa reticularis ; but the loop havingits connection with the spiral lamellae at a point relatively moredistant from their origin on the hinge plate, and passing over,or in front of the BRACHIOPODA. Family III.—Ehynchonellid^e.*Eatonia, Hall, 1859. Dedicated to the late Professor Amos Eaton. Examples, Atrypa peculiaris, Conrad; A. singularis, Yanuxem. Shell like that of Rhynchonella; the xower half of the ventralvalve with a broad deep sinus. Valves articulating by meansof two teeth in the ventral valve, with corresponding sockets inthe dorsal valve, and a median septum embraced between thedeeply bifurcating cardinal process of the opposite one. Dorsal valve with four crural processes; in the ventral valvethe dental plates are represented by elevated lamellae surround-ing the muscular impression, which is much stronger and differsin some respects from that of Rhynchonella. Fossil, 1 species. Upper Silurian. United States. Camerella, Billings, 1859. Examples, C. Volborthi, Billings; Atrypa extans, Hall. Sy
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