YOLDIA. 159 



twentieths of an inch ; height, five twentieths of an incli ; breadth, 

 three twentieths of an inch. 



Found in the stomachs of fish caught off Nahant and Plymouth ; 

 not common. 



This small shell might at first be regarded as the young of some 

 other species. But the central position of the beaks, the number of 

 teeth, and its crescentic or boat-shaped form, are good characteris- 

 tics. The size above indicated is about one third larger than that 

 of the specimens usually found. 



Yoldia sapotilla. 



Fig. 61. 



Shell elongated-ovate, sub-equipartite, sub-rostrated, tumid at the beaks, with 

 a slight flexure under the posterior tip, pale yellowish-green, polished ; teeth 

 about sixteen on each side. 



Nucula sapotilla, Gould, Inv. Mass. 100, fig. 61 (1841). — De Kay, Nat. Hist. New 



York, 180, pi. 13, fig. 220. — Sowerby, Tlies. Conch. (Nucula) fig. 16. — PIanley, 



Recent Shells, 170, pi. 20, fig. .3. 

 Leda sapotilla, Stimpson, Shells of New England, 10 (1851) ; Inv. Gr. Manan, 20. — S. 



Smith, Moll, of Long Island, 15, and Ann. N. Y. Lye. vii. — Reeve, in Belcher's 



last Arct. Voy. ii. 397. 

 Yulilia sapotilla, Packard, Mar. An. of Labrador, 13 (1861). — Stimpson, Check Lists. 



Shell ovate, prolonged, thin, fragile, translucent, the beaks a little 

 in advance of the centre, not elevated, but considerably inflated 

 laterally ; anterior half regularly semi-oval ; posterior portion nar- 

 rowed and compressed, the line running from the 

 beaks to the posterior tip straight, and rendered ^J!5l^^' 



sharp by the compression of a very narrow portion 

 of the margin ; beneath the tip is a truncation or 

 shallow indentation of the margin, bounded by a „ 



a ' J Y. sapotilla. 



wave-like swell passing from the beaks to its an- 

 terior termination ; surface marked only by exceedingly minute con- 

 centric lines, and covered by a very thin and glossy epidermis of a 

 light yellowish-green color, with an occasional narrow zone of a 

 darker color ; within pearly white ; cavity of the cartilage deep and 

 triangular ; teeth about sixteen or eighteen on each side, long and 

 pointed, very small and crowded at the centre. Length, nine tenths 

 of an inch ; height, four fifths of an inch ; breadth, three tenths of 

 an inch. 



Inhabits the vicinity of Cape Cod, where it may be found in the 

 stomachs of fishes, and also by dredging. Many specimens have 



