free movement forward and backward 

 but no sideswaying. Close behind the 

 spine is another powerful saddle-hinge, 

 surmounted by the merest rudiment of a 

 spine which constitutes the "cftch" of 

 the trigger. When it is bent forward, as 

 it may be at the wi'l of the fish, its ex- 

 tremity is received into a hollow near the 

 base of the trigger, which is thus set, at 

 an angle of forty or fifty degrees, as im- 

 movably as the trigger of a Parker ♦"re- 

 bounder" at half-coc> bv r - 1 -'- j back 

 the catch, the spine is released and may 

 easily , be pressed back into its sheath. 

 This mechanism of the dorsal spines, so 

 curious and (if I may so speak of what is 

 not of human contrivance) so ingenious, 

 is varied in the different gent ' of the 

 family and has given to it the na^e Balis, 

 tides. Some of the forms have several spines 

 in the back-fin, but this has only one.and is therefore class- 

 ed with the "unicorn fishes," or the sub-family Mbnacan- 

 thiiuB (?nonos, single, and acantha, a spine). Professor 

 Gill has made for this fish a special genus which he calls 

 Ceratacanthus [keras, a horn, and acantha, a spine). 

 Its color is like that of a fresh Messina orange, marbled # 

 with white and dark brown. lThe throat and cheeks, 

 up to and in front of the eyes, are whitish, with a beau- 

 tiful opalescence in which blue predominates. The 

 prevailing color gives the fish its specific name and 

 completes the title of Gerataccmthus auvautiacus, the 

 "orange file-fish," or, better still, the "orange unicorn- 

 fish." 



Our friend, Mr. A. Ceratacanthus, was first intro- 

 duced to the scientific world by a gentleman to whom 

 it owes other favors, many and great, Mr. Robert Ful- 

 ton, who caught the first specimen in New York har- 

 bor, August 1, 1814. It had for god-father Samuel L. 

 Mitehill, M. D., Professor of Natural History in the 

 University of New York, Representative in Congress, 

 &c, and was first noticed in a paper entitled "The 

 Fishes of New York, Described and Arranged." read 

 before the "Literary and Philosophical Society of New 

 York" on the 8th- of December, 1814. Brought to no- 

 tice by the inventor of the steamship, christened by the 

 father of American ichthyology, under the auspices of 

 a learned society whose successor New York cannot at 

 this day show, its record is certainly a creditable one. 

 Its connections, too, are extensive, for no less than forty 

 of the common fishes of the east coast of North Amer- 

 ica claim Professor Mitehill as sponsor and bear his 



