270 



MANUAL OF THE MOLLUSCA. 



behind ; margins even ; pallial line with a small sinus ; mnbonal area with a 

 linear impression joining the anterior adductor. 



Animal furnished with two partially-united, slender, unequal, siphonal 

 tubes (Forbes) ; gills narrow, plume-like, deeply laminated, attached through- 

 out ; mantle-margin with small ventral lobes forming by their apposition a 

 third siphon. 



Distr. 30 sp. Northera and Arctic Seas , 10 — 180 fms. Siberia, Mel- 

 ville Id. Mass. Brit. Medit. Cape, Japan, Australia. 



Fossil, 110 sp. TJ. S. Europe; S. India. 



Fig. 182. Yoldia n. sp. y- Antarctic Expedition. 



(From a drawing by Albany Hancock, Esq.) The internal organs are represented 

 as seen, through the mantle, on the removal of the right valve. 



o, a, adductors; p,p, -pedal muscles; Z, ligament; ^, gills; s, siphons (much con- 

 tracted); t.c, labial palpi and appendages; i, intestine; /, foot; x,x, lateral muscles 

 of the foot ; m, pallial line. 



Suh-ge7ins, TolcHa, MoUer (dedicated to the Countess Yoldi). Y. myalis, 

 PL XVII. fig. 21. Shell oblong, slightly attenuated behind, compressed, 

 smooth or obliquely sculptured, with dark olive shining epidermis ; external 

 ligament slight ; cartilage as in Leda ; pallial sinus deep. Animal with the 

 branchial and anal siphons united, retractile ; palpi very large, appendiculate ; 

 giUs nan-ow, posterior ; foot slightly heeled, deeply grooved, its margins 

 crenulated ; intestine lying partly close to the right side of the body, and 

 producing an impression in the shell ; mantle-margin plain in front, fringed 

 behind ; destitute of ventral lobes. Bistr. Arctic and Antarctic Seas ; Green- 

 land, ]Mass. Brazil; Nonvay, Kamtschatka. Fossil, Iliocene — . (Crag and 

 Glacial deposits.) England, Belgium. 



SoLENELLA, Sowerby. 



%^, S. Norrisii, PL XVII. fig. 22. S. ornata, fig. 23. 

 Syn. Malletia, Desm. Ctenoconcha, Gray. Neilo, Adams. 



