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Yoldia obiusa. M. Sars. 



Testa tenuissima, alba, Isevis, perparum convexa, elliptica, raaxime inequilatera, antice 

 anguste rotundata, postice altior et rotundato-truncata, epidermide luteo-virente, iiitida, cou- 

 centrice tenui-striata. Margo dorsalis posticus fere rectus, ventralis paruni arcuatus. Ura- 

 boncs parvi. Fovea ligamenti minuta longitudinalis; ligamentum vero externum magnum et 

 prominens. Denticuli cardinales parvi, antice 11 — 15 postice IS — 27. 



Animal siphonibus disjunctis, anali perlongo et angusto, branchiali brevissimo prse- 

 ditum; tentaculis pallialibus singulis valde elongatis filiformibus in vicinia siphonum. 



Longit. testifi majorum 13 Mm., altit. 8 Mm., crassit. (valvarum ambarum) 5 Mm. 



Habitat ad oras Norvegise pluribus locis in prof. 200 — 500 orgyar. 



Of the species hitherto known it resembles most the Lcda obcsa Stimpson (Shells 

 of New England, p. 10. tab. 2. tig. 1.), but is more than twice as large (L. obesa is only 6 

 millimetres long) and has the posterior side both longer and higher; and lastly the cardinal 

 teeth (which in the L. obesa are according to Stimpson, dent. ant. 10, post. 12,) are more 

 numerous, viz. dent. ant. 11 — 15, post. 18 — 27. 



4. Pecchiolia abyssicola. (M. Sars). 



(PI. 3. fig. 21—43.) 



Lyonsiella abyssicola. M. Sars. Vid.-Selskabs Forhandlinger for 1868 p. 257. 



This remarkable deep-sea form was first discovered by me at Lofoten, at the consi- 

 derable depth of 300 fathoms, and was noted by my father 1. c. as a new genus and species 

 under the denomination Lyonsiella abyssicola. It has been subsequently rediscovered during 

 the expeditions of the Porcupine, at still greater depths in the Atlantic Ocean, and referred 

 by Jeffreys, the first and most thorough conchologist of our time, to the genus Pecchiolia, 

 Meneghini (Verticordia, Searles Wood) of which we have hitherto known only one single living 

 species from the tropical oceans, and some few fossils from the chalk formations. The animal 

 of the Pecchiolia has hitherto been entirely unknown; so that we have only had the exterior 

 characters (the shell) to guide us in determining its systematic place, of which also different 

 authors have had very different conceptions. The discovery of a living form of this genus in 

 our northern ocean is therefore of great interest to us; as its proper place in the system 

 can thereby be ascertained with greater accuracy. 



In preparing the following description, I have had rather detailed notes of my Father 



to consult. 



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