[9] FAUNA OF OUTER BANKS, VINEYARD SOUND, ETC. 649 



concave in the middle, and nndnlated by several faint broad ribs ; it 

 recedes posteriorly, and a broad, concave furrow separates it from the 

 small posterior area, which is without ribs, and has a prominent rounded 

 edge. The surface is finely granulated, lines of growth evident. The 

 interior is pearly, angulated by a deep groove, corresponding to the 

 largest external rib. The dorsal hinge-line is nearly straight poste- 

 riorly, and strongly incurved anteriorly, in the right valve it projects 

 inward, but not in the left ; in the right valve there is a small rounded 

 tubercle, a little back of the beak 5 from below this a short rib-like 

 proces.s runs back below the deep, partiallyinternal cartilage-pit, which, 

 extends forward and upward under the beak as a narrow furrow. An- 

 terior nuiscular scar deep; i)Osterior one larger, ovate, less distinct; 

 sinus small. Length, 25"""; height, 20'"»; breadth from side to side, 



QO mm 



Station 947: ol2 fathoms. One pair of fresh valves, dead. 

 This and the preceding were ))oth taken by means of the "rake- 

 dredge." 



Diplodonia tt(r<jif](i Verrill and Smith. 



Shell large tor the genus, round-ovate, a little longer than high, very 

 swollen ; the two ends nearly equally lounded, the anterior a little nar- 

 rower: ventral edge broadly and regularly rounded; beaks nearly cen- 

 tral, somewhat lorward of the middle, sti'ongly curved inward and for- 

 ward, acute. Surface without sculpture, smooth except for the evident 

 lines of growth. In the right valve there are, opposite the beak, two 

 nearly equal, stout, sharp teeth, separated by a space of about the 

 same width; back of these, and ))artly Joined at base to the posterior 

 one, there is a much larger, broad, stout, obtuse tooth, with a groove 

 on its dorsal side; external cartilage-groove and its lamella are long 

 and narrow, curved. Length, 29""™; height (umbos to ventral edge), 

 25 mm. breadth, 23 •"•". 



Station 950 ; 09 fatlioins. One right valve. 



1882. 



During the summer of 1882 the headquarters of the United States 

 Fish Commission were at Wood's Holl, Mass. The organization of the 

 I^arty was nearly the same as last year.* The special object this year 



"The scientific party associated with the writer in carrying on the dredging opera- 

 tions and making the collections this year consisted of Mr. Richard Rathbnn, Mr. 

 Sanderson Smith, Mr. J. H. Emerton (as artist), Prof. L. R. Lee, Mr. 15. F. Koons, Mr. 

 H. L. Bruuer, Prof. Edwin Linton. Prof. S. I. Smith was with us for a few days. 

 Mr. Peter Parker and E. H. Miner, midshipmen, U. S. N., took charge of the fishes, 

 John B. Blish, midshipman, U. S. N., kept the records of soundings and temperatures, 

 and Capt. H. C. Chester had charge of the dredging apparatus, as in previous years. 

 The drcdgiugs were all made by the Fish Hawk, commanded by Lieut. Z. L. Tanner, 

 U. S. N.\ as during the two previous years. The writer, as usual, had general charge 

 cf these explorations, and of the investigation of the invertebrate fauna. 



