1^2 Linnaan Society : — 



fishes. MM. Cuvier and Valenciennes in their ' Hist. Nat. des 

 Poissons,' torn. viii. p. 57, separated the Tunnies from the Mackerels 

 (Scomber), in consequence of the "remarkable disposition of the 

 scales on the thorax, which are larger and more unpolished than 

 the others, and form around that part a sort of corselet?" They 

 also describe the corselet of the Common Tunny thus : — " Le corselet, 

 c'est-a-dire cette portion du tronc couverte d'ecailles plus grandes 

 et moins absorbees dans la peau, est considerable." (p. 62.) This, 

 however, would seem to lead to an incorrect view of the smaller 

 scales on the back, which are, as it were, enclosed between two 

 skins, and are placed in a somewhat imbricated manner, resembling 

 the arrangement of the slates upon a roof, and cannot properly be 

 termed " absorbees dans la peau." Mr. Hogg showed the nature of 

 the piece of the external covering which the fishermen had cut oflF 

 the back ; the outside skin being of a dark, or nearly black colour, 

 and of a coriaceous substance. The white scales, imbedded in it, 

 are similar to those forming the corselet near the gill-covers, but 

 they are much smaller, and so closely placed by one overlapping the 

 other, that they constitute a perfect defence against nearly every 

 kind of danger. The piece so cut off the back of the fish, which 

 was done with some difficulty, resembling a portion of a shield, 

 would seem to be (from the close disposition of the osseous plates 

 or scales enclosed between two skins) proof against large shot, or 

 even a ball from a musket. Both the external large plate -like scales 

 forming the corselet, and those, arranged in a slate-like manner, be- 

 tween the skins, are of an irregular, but somewhat round, or oval, 

 shape. When seen from the outside of the external black skin, the 

 plain parts between the extremities of four scales, present, by the 

 overlapping of their edges, a somewhat regular appearance, and are of 

 a nearly uniform size, viz. about half an inch in length, by a little 

 more than one-eighth of an inch in width, and they thus exhibit 

 much of a diamond pattern. 



Mr. Hogg observed, that ichthyologists seem not to have described 

 this remarkable protection, presented by the thick skins, and strong 

 bony interlaminated scales, which is evidently a beautiful provision 

 of Nature to defend these fishes from the attacks of their enemies, 

 and especially those of their greatest foe, the sword-fish. 



Read a paper " On Decaisnea, a remarkable new genus of the 

 tribe LardizabaletB," by J. D. Hooker, Esq., M.D., F.R.S., F.L.S., 

 and Thomas Thomson, Esq., M.D., F.L.S. 



The small family of Lardizabalece, which was first instituted 

 mar.y years ago by Mr. Brown, and chara cterized by the distribution 

 of the ovules over the whole surface of the ovary, was afterwards 

 admirably illustrated by M. Decaisne in a memoir in the ' Archives 

 du Museum.' Though the peculiar distribution of the ovules has 

 always been justly regarded as the most striking characteristic of 

 Lardizabalece, it is by no means the only peculiarity of the order, 

 which may be distinguished from all its near allies by a considerable 

 number of very striking characters, sufficiently proving the distinct- 



