456 Prof. Reid on the Vogmarus Islandicus. 
colonies. These are startling facts, and go far to disprove Mr. 
Alder’s doctrine, that the tube-like fold of the mantle is for the 
entry and regulation of branchial currents, which, even if they 
occasionally occur from spring tides and other causes, can only 
be in action for a very short time during the twenty-four hours. 
But I believe that in certain localities these creatures are not 
immersed in the sea-water for months together during the calms 
of summer. Many individuals of course inhabit lower levels, 
and will be more or less submerged. 
Kellia rubra, then, may almost be considered a terrestrial 
bivalve. When it detaches itself from its hyaline delicate fila- 
mentary byssus, as it frequently does, to change place, food, and 
remove into more humid quarters, it is unable by its long slender 
foot to drag itself over the interstices of the fuci and the aspe- 
rities or other matters in which it may happen to be settled 
without the aid of an additional power, which I am inclined to 
think is furnished by the extended fold of the mantle; and this 
supposition appears to receive strong support by the isochronal 
action of the foot and fold. | : 
I am, Gentlemen, your most obedient servant, 
| WiiiaM CLARK. 
XLVII.—An Account of a Specimen of the Vaagmaer, or Vog- 
marus Islandicus (Trachypterus Bogmarus of Cuvier and Va- 
lenciennes), thrown ashore in the Firth of Forth. By Joun | 
Rerp, M.D., Professor of Anatomy and Medicine in the Uni- 
versity of St. Andrews. 
{ With a Plate. } 
Tuis fish was sent me on the 7th of April 1848 by Dr. John 
Berwick of Elie, near which place it was cast ashore dead. It 
was perfectly fresh when I received it ; but the dorsal and caudal 
fins were damaged, and the ventral fins were entirely wanting— 
a condition, which, from the brittleness of these parts, is gene- 
rally found in the adults of this genus of fishes*. Its characters 
showed distinctly that it belonged to the family Teenioides and 
genus Trachypterus of Cuvier and Valenciennes, and on compa- 
ring these with the descriptions of the species of Trachypterus 
given in the work of Cuvier and Valenciennes, and that of the 
Trachypterus vogmarus or bogmarus by Protessor John Reinhardt 
of Copenhagen, contained in the Supplement to the Ist edition, 
* Histoire naturelle des Poissons, par Cuvier et Valenciennes, tome x. 
pp. 314-15, and pp, 325-26. — Paris, 1835. 
