874 1'IIOCEEDINGS OF THE NATIONAL MUSEUM. VOL.XX. 



The subgeuus Pseudomalletia^ proposed by Fischer for M. obtusa, was 

 based on an erroneous description of the siphon tubes. 



The following are some of the known species: 



M. chilensis Desmonlius, Valparaiso (Type); M. obtma (Sars) Morch, 

 from off Cape Fear, North Carolina, northward; M. polita Yerrill and 

 Bush, off Delaware Bay; M. abyssornm Verrill and Bush, off Chesa- 

 peake Bay; M. cnneata Jeffreys, North Atlantic; M. palli<l Smith, 

 Mid-South Atlantic; M. arrouana Smith and M. dunlceri Smith, 

 Pacific; and J[. beUardii Seguenza, fossil. 



MALLETIA OBTUSA (M. Sars) Morch. 

 (Plate XC VII, fig. 4.) 



Yoldia obtusa G. O. SARS, Remarkable Forms of Animal Life, p. 23, pi. in, figs. 

 16-20, 1872. 



Malletia obtusa G. O. SARS, Mollusca Keg. Arcticsc Norvegiio, p. 41, pi. 19, figs. 

 3, a-l>, 1878. JEFFREYS, Proc. Zool. Soc., London, p. 586, June, 1879. VER- 

 RILL, Trans. Conn. Acad., VI, pp. 226, 280, 1884; Expl. Albatross, Report U. S. 

 Com. Fish and Fisheries for 1883, p. 576, 1885. SMITH, E. A., Report Voy. 

 Challenger, Zool. Lamellibrauchiata, XIII, p. 245, 1885. BALL, Bull. U. S. 

 Nat. Mus., No. 37, p. 46, 1889. BUSH, Bui. Mas. Comp. Zool., XXIII, p. 234, 

 1893. LOCARD, Campague du Caudan, Anuales de I'Universite" de Lyon, 

 p. 202, 1896. VERRILL and BUSH, Amer. Journ. Sci., Ill, p. 57, fig. 9, 1897. 



The soft parts of several specimens, rather poorly preserved in alco- 

 hol, have been examined. They have a large foot with an ovate disk 

 pointed in front and minutely crenulated. The siphon tube is rather 

 long and slender, in some cases not entirely retracted within the shell; 

 it appears to contain both the branchial and anal tubes which are 

 closely united quite to the simple tips; at the inner base, there is a 

 well-marked siphonal septum. The gills are small, elongated, pointed 

 posteriorly, and have the structure usual in the family. The palpi are 

 rather large, elongated, with re volute margins; the palpal tentacle is 

 very long and slender, and in the contracted state variously bent with 

 the edge much convoluted. No pallial tentacle was found at the base 

 of the siphon. 



In our collection there is a large series of this species; the form is 

 pretty constant and in nearly all cases is more oblong than the Euro- 

 pean species, as figured by G-. O. Sars. The small specimens are com- 

 pressed while the large ones are a little swollen. The umbos are 

 small, but slightly elevated; the beaks are very small, turned directly 

 inward, and are almost in contact with the margin, so that they are 

 generally worn away in the larger specimens. Directly under, and 

 partly in the beaks, and also cutting more or less into the thickness of 

 the external side of the hinge-margin, there is a small notch, or shallow 

 excavation, which is occupied by a special portion of the ligament 

 that probably represents a remnant of a degenerated resilium. The 

 true ligament is well developed and prominent for about one-half the 

 length of the hinge-margin, then becomes abruptly thinner and nar- 



