160 Transactions. — Zoology. 



are in a natural position (fig. 9) it is completely enveloped 

 by the sacculations. Its internal walls are richly plicated. 

 The albumen gland very large, and the hermaphrodite duct 

 densely convoluted. The right lobe of the liver, including the 

 hermaphrodite gland, was torn off and remained in the shell 

 when extracting the animal. 



The systematic position of fumosa has already received 

 some attention. Ancey, in Journal de Conchoiogy, xlix., p. 12, 

 places it in Paryi^hanta, and refers to it as an interesting 

 Antarctic species. Suter, in the same publication (p. 316), at 

 once throws doubt on its pertinence to Paryyhanta. To this 

 Ancey replies (J. de C, li., p. 44) that until anatomical in- 

 vestigation disproves it the species may by shell characters 

 fairly be assumed to be a Paryphanta. 



The most striking peculiarity in the anatomy of the several 

 known species of Paryphanta is the marked difference in their 

 genital organs. The difference is chietiy centred in the re- 

 ceptaculum seminis ; the contour of this organ is so distinct 

 in each species that, when added to the minor difference in 

 other organs, it presents a type of genitalia unusually distinct 

 amongst species of the same genus. P. busbyi can scarcely 

 be compared with the other members, its genital organs are 

 almost totally different ; but this condition is probably due to 

 degeneration. On the other hand, the general anatomy does 

 not appear to present any important differences, except the 

 form of attachment of the buccal-mass retractor in P. fumosa. 

 This divergence from the typical form is an important feature, 

 for as a rule the form and position of the principal muscles in 

 a genus or family show a far smaller range of variation than 

 organs such as the jaw, dentition, or genitalia ; however, 

 apart from this feature, the arrangement of the muscles, as 

 previously stated, is identical wuth P. hochstctteri ; also, there 

 IS a mass of evidence from totally diverse, uncorrellated organs 

 which is quite in accord with Paryphanta. 



^'g-J-[ Shell. 



EXPLANATION OF PLATE VL 

 Paryphanta fumosa, Ten. -Woods. 



3. Buccal mass, &c. 



4. Buccal-mass retractor muscle, form of attachment. 



5. Teeth. 



G. Salivary gland, ventral side. 



7. Pedal gland. 



8. Pallial region. 

 (J I 



, „■ • Generative organs 



