206 A. JEJ. Verrill — Mollusca of the Nexn England Coast. 



forming an elongated channel ; it is distinctly visible from the out* 

 side, owing to the translucency of the shell. 



Length of shell, 3-5'"™ ; breadth, 2-5'""'; height, about 1"^'". 



Station 2105, N. lat. 37° 50', W. long. 73° 03' 50", in 1395 fathoms 

 (No. 38,072). Two specimens, living. 



The animal has a short, broad-ovate foot, siibtruncate in front, 

 with the edge frilled. Frontal disk rather large, broad, semicircular 

 or crescent-shaped, with the angles extending back in a large obtuse 

 lobe on each side. Buccal area semicircular; mouth surrounded with 

 four convex elevations, one before and one behind it, and one on 

 each side. Tentacles slender, tapering, acute. Eyes apparently 

 M'anting. No cirri on mantle. 



POLYPLACOPHORA. 



PlaCOphora (EuplaCOphora) Atlantica VerriU and Smith, MSS. 

 Verrill, Amer. Journ. Sci., vol. xxiv, p. 365, Nov., 1882. 

 Plate XXX, figures 1, la, \h. 



Outline broad-ovate. Marginal membrane very broad anteriorly 

 and narrow posteriorly. It increases gradually from the posterior 

 end to a point opposite the fifth plate, where it suddenly expands 

 into a broad round front, with the breadth one-third greater than the 

 greatest breadth of the shell, and projecting forward to a distance 

 equal to one-half the length of the shell. The marginal membrane is 

 thick, leathery, and scabrous, everywhere closely covered with 

 minute spinules ; the lower surface anteriorly shows many radiating 

 grooves (not distinct in the smaller examples) ; between these are 

 rows of slightly raised small verrucse, covered with small spinules. 

 The inner edge, or mantle-border, is sharply defined, enclosing an 

 elliptical area around the head and gills, with a well-marked poste- 

 rior sinus; its front edge is divided into about seven digitations, the 

 anteriov ones rather long, tapering, and tentacle-like, but coriaceous 

 and covered with fine spinules, like the rest of the marginal mem- 

 brane. Cephalic hood large, broad-lunate ; foot relatively small, 

 ovate. Gills numerous (in the largest about sixteen on each side), 

 extending nearly the whole length (more than two-thirds) of the 

 foot, but reaching neither end of it. 



The shell is broad-ovate, slightly carinated in the middle ; valves 

 short, broad, the posterior ones decreasing rapidly in breadth, the 

 last one very small. Anterior valve short, very broadly routided in 

 front ; posterior edge with a very obtuse reentrant angle and a 



