NO. 1139. DEEP-WATEE MOLLrSCA VEREILL AND BUSH. 8H1 



But one specimen from station 199, oft' Thatchers Island, in 98 

 fathoms, 1878, has been referred to this species, besides the type 

 specimens (No. 38420) station 1093, off Marthas Vineyard, in 349 

 fathoms, 1882. 



YOLDIELLA Verrill and Bush, 1897. 

 Yoldiella VERRILL and BUSH, Amer. .Tourn. Sri., Ill, pp. 55, 63, January, 1897. 



Type. Yoldiella lucid a (Loven). 



This group includes a large number of small, mostly deep-sea species 

 with glossy, iridescent, ovate, and usually wedge-shaped shells, nearly 

 always having a slight antero-ventral sinuosity, which feebly defines 

 an obscure, blunt, rostal region, without any definite carinatiou. The 

 shells do not gape, but close tightly except that at the rostral angle of 

 some species there may be a slight divergence. The internal cartilage, 

 which is often relatively large, occupies a simple notch which inter- 

 rupts the hinge-margin more or less completely and generally shows 

 externally in a dorsal view; the notch usually terminates within, on 

 the inner or inferior surface of the hinge-plate and is often bounded 

 within by a slight ridge. A weak external ligament is present on the 

 postero- dorsal margin. A relatively small pallial sinus has been 

 observed in several of the species, but is usually indistinct. The 

 siphon tubes, as observed in a few of the species, are slender and 

 united for more than half their length. 



The following are some of the species: Y. lucida (Loven) Yerrill and 

 Bush, T. iris Yerrill and Bush, and var. strictci Verrill and Bush, 

 Y. inflata Verrill and Bush, Y. inconspicua Verrill and Bush, and Y. 

 Jeffrey si (Hidalgo) Verrill and Bush, off Cape Hatteras, North Caro- 

 lina, northward; T. dissimilis Verrill and Bush, north of Cape Hat- 

 teras, North Carolina, northward; Y. fraterna Verrill and Bush, off 

 Chesapeake Bay, northward ; Y.'minuscula Verrill and Bush, and Y. 

 subequilatera Verrill and Bush, off Delaware Bay, northward; Y. fri- 

 yida (Torell) Verrill and Bush, and Y. curia Verrill and Bush, oft' Mar- 

 thas Vineyard, northward; Y. subangulata Verrill and Bush, and 

 r. lenticula (Moller) Verrill and Bush, var. amblia Verrill and Bush, 

 Gulf of Maine; Y. expanm (Jeffreys) Verrill and Bush, oft' Grand 

 Banks; Y. pachia Verrill and Bush, southern; Y. lioylei (Smith) Verrill 

 and Bush, North Pacific. 



YOLDIELLA LUCIDA (Loven) Verrill and Bush. 



(Plates LXXVII, fig. 2; LXXX, fig. 3.) 



Yoldia lucida LOVKN, Index Molluscorum, p. 34, 1846. 



fLeda obcsa STIMPSON, Proc. Boston Soc. Nat. Hist., IV, p. 113, 1851; Shells New 



Eng., p. 10, pi. n, fig. 1, 1851. 



Leda lucida JEFFREYS, British Conchology, V, p. 173, pi. c, fig. 1, 1869. 

 Yoldia obesa GOULD, Rep. on Invert, of Mass., Binuey's ed., p. 155, tig. 463, 1870. 

 Leda obcsa TRYON, Amer. Mar. Conch., p. 184, pi. xxxvm, figs. 500, 501, 1873. 



