1881.] 'lightning* AND 'porcupine* EXPEDITIONS. 697 



Fossif, 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 Spatanr/us purpureus 

 — the former at the top, and the latter at the hottom or anal end. 

 Moray Firth : of large size on the shore, smaller in deep water 

 (Mc Andrew). 



t/ 2. MoNTAcuTA pellucida', Jeffreys. (Plate LXI. fig. 3.) 

 Shell oval, convex, thin, transparent, and glossy : sculpture, 

 strongly marked concentric lines of growth, and under the micro- 

 scope minute irregular scratches arranged lengthwise : colour whitish, 

 but partially clouded in consequence of the specim.en being " dead " 

 or not fresh : tnargins 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 ; beahs prominent, calyciform, 

 placed nearly in the middle : hinge-line obtuse-angled, excavated in 

 the middle, occupying rather more than one fourth of the circum- 

 ference : 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 an- 

 terior side is twice as long as the other : inside glossy, plain-edged ; 

 scars slight. L. 0-J5, B. 0-2. 



' Porcupine' Exp. 1870: Mediterranean ; St. Adventure Bank, a 

 single valve. 



Compare the above description with that oi 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, Friclc. 

 ■^ Montacuta (?) voringi, Friele, N. Mag. f. Naturv. xxii. B., 3. H. 

 (separat-aftryck) p. 1, f. 1, la. 



' Porcupine ' Exp. 1869, St. 36. 1870 : Atlantic, 9, 24, 26. 



Distribution. Soguefiord, Norway, 630 fms. {Friele) ! ; Palermo, 

 87 fms. (Monterosato)\ 



Provisionally named by nie M. cuncata. I have both valves ; and 

 I cannot see any generic difference in the hinge between this shell 

 and M. bidentata, notwithstanding the remark of my friend Herr 

 Friele, who described a single valve only. 



^ 4. MONTACUTA DONACINA, S. V. Wood. 



Montacuta ? 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. 



' Trausparent. 



Proc. Zool. Soc— 1881, No. XLV. 45 



