On a new species of the genus Cephalopterus. 23 



rock. It has been ascertained that the country along the base 

 of the Rocky Mountains, a few degrees to the southward of 

 the Missouri, contains extensive beds of Amygdaloid,* in con- 

 nexion with which is found a substance similar in aspect and 

 character to the mineral under consideration, and light enough 

 to float on water, it will not perhaps be thought an extrava- 

 gant conjecture to suppose that the reputed Pumice stone of 

 the Missouri, is not a product of volcanic or pseudo-volcanic 

 fires, at present in a state of activity ; but a variety of Amyg- 

 daloid brought down by the rains and the currents of water, 

 from an extensive formation of Trap rocks in that quarter. 



Description of a new and gigantic species of the genus Cepha- 

 lopterus, of Dumeril. By S. L. Mitchill, M. D. Read 

 September J 5, 1823. 



CEPHALOPTERUS. 



Body much depressed, with five or six branchial openings 

 on each side beneath, rostrum with two elongated fins, sustain- 

 ed by articulated rays. Tail long, slender, much narrower 

 than the body. 



Species. — C. Vampyrus, Oceanic Vampyre. Breadth of 

 the body exceeding its length ; mouth nearly terminal, with- 

 out teeth ; a vertical fin on each side of the mouth projecting 

 forwards ; tail Unarmed. — PL 2. 



On the 9th day of September, 1823, a fish considerably dif- 

 ferent from any I had seen before, and unlike all the descrip- 

 tions that 1 could find in the books, was brought to New- 

 York. It had been taken in the Atlantic ocean, near the en- 

 trance of Delaware bay, by the crew of a smack. They had 



* For a particular description of the amygdaloid of this Trap forma- 

 tion, see the Account of the Exploring Expedition commanded by Major 

 Long, vol. ii. p. 80. 



