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Show 1878.] 'LIGHTNING' A N D 'PORCUPINE' EXPEDITIONS. 409 valuable work of Professor Seguenza, notwithstanding that my of the distinctive character of certain species do not accord with his. Genus II. TEREBRATELLA. TEREBRATELLA SPITZBERGENSIS, Davidson. (Plate XXIII. fig. 2; loop.) Terebratella spitzbergensis, Dav. in Ann. & Mag. N. H. 1855, xvi. p. 442, pl. x. fig. 3 : B. C. ii. p. 2; v. p. 164, pl. xcix. fig. 3. Spitzbergen, Iceland; ' Valorous ' Expedition, Wellington Channel, Davis Strait, Gulf of St. Lawrence, North Japan, and Shetland : depths 20-690 fathoms. Genus III. ARGIOPE. Typical. Having three septa. 1. A R G I O P E DECOLLATA, Chemnitz. Anomia decollata, Ch. Conch. Cah. viii. p. 96, pl. 78. figs. 705 a-d. Argiope decollata, B. C. ii. p. 18; v. p. 104, pl. xix. fig. 3. ' Porcupine' Exp., 1870 : Atlantic, St. 24, 292 f.; 36, 364 f. Mediterranean, 58, 50 f. ; Adventure Bank, 92 f. Guernsey, South-west of France, Atlantic coasts of Spain, Mediterranean, Adriatic, JEgean, Madeira, Canary Isles: 18-130 f. In some specimens, recent and fossil, the ribs are evanescent or scarcely perceptible. Size variable. Synonyms : Anomia detruncata, Gmelin ; Terebratula aperta, De Blainville; T. cardita and T. urna-antiqua, Risso; T. ungula, Retz ; T. pectiniformis, O. G. Costa ; T. dimidiata, Scacchi. Subgenus Cistella. With a single septum. 2. ARGIOPE NEAPOLITANA, Scacchi. Terebratula neapolitana, Sc. Oss. Zool. 1833, ii. p. 18. Mediterranean, Adriatic, iEgean, and Canary Isles: 30-320 f. The number of ribs varies from two to eight, some specimens being quite ribless ; and the shape and size are also very variable characters, as in A. cuneata. From that species A. neapolitana may be distinguished by the inner margin in the latter being furnished with a numerous row of small and short ridges, which become tubercular in front, by the anterior margin being indented in the middle, and by the septum in the lower valve being notched across. In some specimens, which are more transparent than usual, the marginal ridges can be seen outside. Philippi has, in the figures given in his first volume, evidently confounded the present species (his Terebratula seminulum) with Platydia anomio'ides, which it seems he did not then know. Terebratula cordata, Risso; T. seminulum, Ph.; Orthis bifida, Costa; A. forbesi, Davidson. |