862 PROCEEDINGS OF THE NATIONAL MUSEUM. VOL.XX. 



Toldia olesa VERRILL, Amer. Journ. Sci.,VII, pp. 46, 412. 503, 1874. SMITH and 

 HARGER, Trans. Conn. Acad., Ill, pp. 18, 23, 1874. YERRILL, Explorations 

 ( '.isco Bay, pp. 352. 368, 1874 ; Invert. Auim. Vineyard Sd., p. 396, 1874. 



Portlandla lucid a G. O. SARS, Mollusca Reg. Arcticaj Norvegiae, p. 37, pi. 4, figs. 

 8a, 86, 1878. 



Ledu lucida JEFFREYS, Proc. Zoiil. Soc., London, p. 578, 1879. 



Toldia lucida VERRILL, Trans. Conn. Acad., V, pi. XLIV, fig. 1, 1882 ; vi, p. 279, 1884 

 (in part); Expl. Albatross, Eeport U. S. Com. Fish and Fisheries for 1883, 

 p. 576, 1885 (in part). BUSH, Bull. Mus.Comp. Zoo.l, XXIII, p. 233, 1893. 



YoJtliella lucida VEKRILL and BUSH, Amer. Jonru. Sci., Ill, p. 55, fig. 14, January, 

 1897. 



Shell small, swollen, subovate, with a posterior angle, smooth, or 

 more or less striolate, iridescent. The umbos are but little prominent, 

 in front of the middle ; the beaks interrupted or obliterated by the dark 

 central cartilage which occupies a relatively large notch intersecting 

 the entire thickness of the hinge-margin. The antero dorsal margin is 

 convex with the edge a little expanded; it slopes rapidly from the 

 beak to the anterior end which is obtusely rounded; the ventral mar- 

 gin is broadly and regularly curved nearly to the posterior end where 

 there is a slight protrusion corresponding to a faint undulation of the 

 surface; the posterior end is somewhat wedge shaped, a little com- 

 pressed and tapered, and makes a distinct but obtuse angle where it 

 joins the dorsal margin in line with a rounded posterior ridge running 

 from the convex part of the umbos; just below the angle the margin is 

 usually convex or subtruncate and without any definite lower angle; 

 the posterior dorsal margin slopes less rapidly than the anterior, is 

 nearly straight with the edge compressed and a little expanded into a 

 thin keel which is usually slightly convex in the middle. The hinge- 

 margin is strong, somewhat prolonged, scarcely augulated in the middle; 

 the part in front of the chondrophore is well-arched and bears, in the 

 largest specimens, nine or ten, sharp, prominent, angular teeth, of which 

 two or three nearest the beak are quite small; the posterior portion is 

 nearly straight, a little longer and narrower than the anterior and bears 

 about eleven thin, sharp, erect teeth, counting one or two minute proxi- 

 mal ones; a thin smooth margin extends outside both series of teeth. 

 The cartilage-pit is relatively large, in the form, of a notch, and cuts 

 through the hinge-margin into the substance of the beak itself; it is 

 occupied by a dark brown resilium which usually shows plainly exter- 

 nally. Just in front of the cartilage-pit on its border within the series 

 of teeth, there is a small conical, tooth-like process in both valves. The 

 ligament is thin and delicate. Externally the shell is covered with a 

 glossy, yellowish, or pale olive epidermis which reflects brilliant pris- 

 matic colors; the surface is marked by faint lines of growth and fre- 

 quently also with fine concentric grooves or sulci, especially toward 

 the ventral and anterior margins; in many specimens these are absent. 



Length of one of the largest specimens, 7 mm.; height, 4.25 mm.; 

 breadth, 3.2 mm. 



Found in small numbers, at many stations, between N. lat. 43 39', 



