Mr. A. Adams on new Mollusca from Japan. 299 



I have examined the marginal nerves in the leaves of a great 

 number of Mosses, and in some instances have seen them ex^ 

 tending from the very cells of the axis or stem to the point, or 

 beyond the point, of the leaf-blade; and these nerves may 

 generally be found when the border of the leaf is described as 

 " cartilaginous " or " thickened/' though their structure, being 

 commonly a soft and juicy prosenchyma, has no relation what- 

 ever to the structure of cartilage, nor to the bryological defini- 

 tion of it " a hard close texture, not tender and succulent." 



The following extracts from my note-book will render it easy 

 for the bryologist to examine these nerves, without the aid of a 

 drawing, particularly as the kindness of Mr. Mitten has made 

 me sure of the identity of the species. 



Atrichum undulatum. Dec. 1859. Very distinct marginal 

 nerves from the stem to the point of the leaf, and Y^Q-Q- of an 

 inch in diameter, the mid-nerve being fully thrice as large. 

 The measurements in this and the following instances are made 

 near the middle of the nerves. 



Fissidens bryoides. Dec. 3, 1859. Marginal nerves very plain, 

 2 2fF f an i* 10 * 1 m diameter, while the mid-nerve is TTIJ . 



Fissidens tamarindifolius. Dec. 23, 1859. Marginal nerves as 

 distinct as in F. bryoides, and Q^-QQ of an inch in diameter, the 

 mid-nerve being ^-g-g. 



Mnium hornum. Jan. 1860. Marginal nerve ^^ of an inch 

 in diameter, extending most plainly from the base to the apex 

 of the leaf, and composed of about three rows of prosenchyma- 

 tous cells remarkably distinct from the contiguous squarish or 

 polyhedral parenchymatous cells of the leaf-blade. 



Bryum capillare. Jan. 1860. Marginal nerves y^o ^ an 

 inch in diameter, scarcely distinguishable from the neighbour- 

 ing cells of the leaf-blade, though portions of the nerve may be 

 sometimes torn off, and it can be traced into the apiculus of the 

 leaf. This leaf is a fair specimen of a connecting link between 

 the presence and absence of a plain marginal nerve. 



XXXIV. On some New Genera and Species of Mollusca from 

 Japan. BY ARTHUR ADAMS, F.L.S., &c. 



To the Editors of the Annals of Natural History. 



Tsu-Sima, Straits of Korea, 

 GENTLEMEN, 5th Dec., 1859. 



In the course of our circumnavigation of the Sea of Japan, 

 in H.M.S. ' Actseon/ the dredge was sometimes put in requisi- 

 tion, and, in addition to a better acquaintance with the geogra- 

 phical distribution of marine life which was thereby afforded, 



20* 



