262 REPORT ON ALBATROSS MOLLUSCA DALL. 



with the edges posteriorly thickened or infolded but nearly smooth. 

 The anal opening lias no tube, but forms a simple long ovate slit. The 

 gills are free, except proximally, over two-thirds of the whole length is 

 unattached. The mouth is small, with a narrow raised edge like a 

 Polyzoon epistome, but no palpi. The ovarian and hepatic lobules are 

 attached on each side of the foot and ramify from a central area of at- 

 tachment in a very large number of short stout spongy lobules, recall- 

 ing the digitations of some keratose sponges. The ova are minute and 

 yellowish. The hepatic granules are dark brown or grayish. The 

 whole mass of the geuitokepatic organs nearly fills the mantle cavity, 

 and is larger than all the rest of the soft parts put together. These 

 lobules are not like the pyriform projections of Myonera, each of which 

 projects singly from the rounded surface of the visceral mass, and prob- 

 ably subsides after the period of ovulation. In Cryptodon the whole 

 mass on each side arises from a single small area, and digitates after- 

 ward. 



Cryptodon ftiegiensis sp. uov. 



Plate xiv, Fig. 2. 



Shell large, white, thin, suborbicular ; concentric sculpture of incre- 

 mental lines; radiating sculpture of one sharp groove near and parallel 

 with the posterior hinge-margin, its termination indenting the margin, 

 and a wider shallow sulcus below it also causing a flexuosity on the 

 posterior margin ; an obscure groove anteriorly bounds a lunular area, 

 and there are several faint indications of other radii near those above 

 mentioned ; surface of the valves microscopically grauulous, covered 

 with a mostly dehiscent pale straw-colored epidermis ; valves only mod- 

 erately inflated; ligament long, black, deep-seated; hinge edentulous; 

 interior of shell faintly radiately striate; scars distinct, with rather 

 irregular outlines; margin sharp, simple; maximum longitude of shell 

 25; altitude 21.5; diameter 14.4: vertical from the umbones behind the 

 anterior end 7 mm . 



Hab. — Station 2770, in the Straits of Magellan, in 77i fathoms, ooze, 

 temperature 4G°.9 F. 



This splendid species is oue of the largest recent forms known, and 

 was discovered in fragments which admitted of reconstruction. 



There does not appear to be any fossil species on the coast of South 

 America which is nearly related to C. fuegiensis, but it may be men- 

 tioned that the Venus bisectus Conrad (Wilkes Exploring Expedition, 

 Dana Geological Report, p. 724, pi. 17, fig. 10), afterward referred by 

 Conrad to Cyprina (Am. Jour. Conch., 1, p. 153, 1865) is a fine species 

 of Cryptodon or Axinus. I hope before long to publish a revised list of 

 these Oregonian fossils referred by Conrad to the Eocene, some of 

 which appear to be closely related to some of those forms figured from 

 the Tertiary of Chile by the venerable Dr. Philippi in his latest works. 



