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Show 1881.] 'LIGHTNING* AND'PORCUPINE'EXPEDITIONS. 697 Fossil. Pliocene and Post-tertiary : Norway, Great Britain and Ireland, N. France, and Italy ; 0-80 ft. Synonyms several. The variety nivea is the Tellimya nivea of G. O. Sars, and corresponds with the variety radiata {Syndosmya radiata, Loven) of Scrobicularia alba. Mr. Marshall found this species and M. substriata at Guernsey attached to the spines of the same specimens of Spatangus purpureus -the former at the top, and the latter at the bottom or anal end. Moray Firth: of large size on the shore, smaller in deep water {31 c Andrew). 2. MONTACUTA PELLUCIDA1, Jeffreys. (Plate LXI. fig. 3.) S H E L L oval, convex, thin, transparent, and glossy : sculpture, strongly marked concentric lines of growth, and under the microscope minute irregular scratches arranged lengthwise : colour whitish, but partially clouded in consequence of the specimen being " dead" or not fresh : margins somewhat truncate at the posterior or smaller side, gently curved in front, expanded at the anterior side, and sloping from the beak on each side ; beaks prominent, calyciform, placed nearly in the middle : hinge-line obtuse-angled, excavated in the middle, occupying rather more than one fourth of the circumference : cartilage-pit small, lying underneath the beak, with thickened edges: hinge-plate narrow and thin : teeth (in the only valve here described) consisting of a laminar lateral, which projects beyond the hinge-plate, on each side of the beak ; that on the anterior side is twice as long as the other : inside glossy, plain-edged ; scars slight. L. 0*15, B. 0*2. ' Porcupine' Exp. 1870: Mediterranean ; St. Adventure Bank, a single valve. Compare the above description with that of M. ferruginosa given in ' British Conchology.' The present species is oval instead of oblong, the posterior margin is not angulated, the beaks are prominent and placed nearly in the middle, and the cartilage-pit is much smaller. 3. MONTACUTA VORINGI, Friele. Montacuta (?) voringi, Friele, N . Mag. f. Naturv. xxii. B., 3. H . (separat-aftryck) p. 1, f. 1, la. 1 Porcupine ' Exp. 1869, St. 36. 1870 : Atlantic, 9, 24, 26. Distribution. Sognefiord, Norway, 630 fms. (Friele) !; Palermo, 87 fms. {Monterosato)\ Provisionally named by me 31. cuneata. I have both valves ; and I cannot see any generic difference in the hinge between this shell and M. Bidentata, notwithstanding the remark of m y friend Herr Friele, who described a single valve only. 4. MONTACUTA DONACINA, S. V. Wood. 31ontacuta1 donacina, S. V. Wood, Mon. Crag Moll. ii. p. 131, t. xi. f. 3, a-c : B. C. ii. p. 216 ; v. p. 178, pi. c. f. 4. ' Porcupine ' Exp. 1869 : St. Lough Swilly. 1 Transparent. PROC. ZOOL. Soc-1881, No. XLV. 45 |