116 DEEP-SEA FISHES OF THE ATLANTIC BASIN. 



ALEPISAURUS, Lowe. 



Alepisaurus, Lowe, Proo. Zool. Soc. London, 1833, 104; Trans. Zool. Soc, i,124. — Cuvier and Valenciennes, 



Hist. Nat. Poiss. xxn. 529. — GiNiHEii, Wiegmann's Archiv, 1860, 121. 

 Alepidosaurus, Gunther, Cat. Fish. Brit. Mus., v, 1864, 420.— Jordan and Gilbert, Bull, xvi, U. S. N. M., 275. 

 Plagyodus, Gunther, Annals and Mag. Nat. Hist., 1867; Challenger Report, xxn, 1887, 203.— Jordan, Cat. 



Fishes, N. America, 1885, 39. 



Body elongate, compressed, scaleless; head compressed; snout produced ; mouth cleft 

 wide; premaxillary long and slender; maxillary thin, long, immovable. Teeth unequal, 

 immovable. Very small teeth run along entire length of intermaxillary. Palatine teeth 

 compressed, pointed, the two or three anterior ones very strong and long, and the pos- 

 terior ones moderate. Teeth in lower jaw similar to those on the palatine bones, one 

 pair in front and two or three pairs in the middle much enlarged. Eye large. Pectoral 

 and ventral tins well developed. Adipose fin of moderate size. Caudal forked. Gill opening 

 very wide. Branchiostegals, v-vn. 



The name Plagyodus, Steller (Pallas, Zoogr. Ross. Asiat., Ill, 383), has been adopted by 

 Dr. Gunther,* but it is doubtful whether Steller used the name Plagyodus in the sense of a 

 Linnaean genus. 



The following discussion of this genus is quoted from Gunther's great work: 



"Like most other deep-sea fishes, Alepidosaurus has been found at widely distant local- 

 ities, and it is probable that in time it will be obtained in tlie intermediate parts of the 

 ocean. Deep-sea fishes are much less subject to differences of climate than those inhabit- 

 ing the coasts or the surface, and therefore we should not be surprised to find the repre- 

 sentatives of one aad the same genus, and frequently even the same species, in high lati- 

 tudes of the northern and southern hemispheres. 



"Every part of the Alepidosauri is so fragile that it is extremely difficult to obtain 

 perfect specimens. It is also impossible to preserve them in spirits without some portion 

 of the dorsal and of the other fins being broken. The entire structure of the dorsal fin is 

 so delicate, that it must even be liable to injury and alteration of outline while the fish is 

 in its native element. The fibrous ligaments connecting the vertebra are very loose and 

 extensible, so that the form of the fish is easily lengthened when its body is slightly 

 stretched. Therefore no reliance whatever is to be placed on trivial specific distinctions 

 founded on the form of the dorsal fin and on the relative proportions of the head and body. 

 A comparison of the two figures of A. ferox, given by Lowe, will show the truth of this 

 observation. 



"The loose connection of the single parts of the body is found in numerous deep sea 

 fishes, and is merely the consequence of their withdrawal from the pressure of the water to 

 which they are exposed in the depths inhabited by them. When within the limits of their 

 natural haunts, the osseous, muscular, and fibrous parts of the body will have that solidity 

 which is required for the rapid and powerful movements of a predatory fish. That the 

 fishes of this genus belong to the most ferocious of the class is proved by the dentition and 

 the contents of their stomach; but it is worthy of notice that although the mouth is so 

 deeply cleft, the lower jaw can not be moved from the upper at a greater angle than about 

 40 degrees. The teeth are constantly changing and it is odd that an ichthyologist like 

 Lowe should have had so much difficulty in recognizing the nature of some immature teeth 

 lying in the gingiva." 



P. Poey has described a specimen from Cuba, under the name of A. altivelis (Poey, 

 Mem. Hist. Nat. Cuba, II, 302), and also referred to another form, which Gill has named 

 provisionally Gaulopus Poeyi (Proc. Acad. Nat. Sci., Philad., 1802, p. 131). 



* Description of a New Genus of Acanthopterygian Fishes. By the Rev. R. T. Lowe, B. A., Corr. Memb. 

 Z. S. (In a letter to the Secretary.) < Trans. Zool. Soc, London, v. I. pp. 123-128, pi. xix, 1835. 



Additional Observations on Alepisaurus ferox. By the Rev. R. T. Lowe, M. A., C. M. Z. S. < Trans. 



Zool. Soc, London, v. I. pp. 395-400, pi. lix, 1835. 



t On Alepidosaurus, a Marine Siluroid Fish. By Dr. Albert Giinther. < Ann. and Mag. Nat. Hist., Series 

 III, v. vi, 150-1. 



Gunther, A. On the identity of Alepisaurus (Lowe) with Plagyodus, Steller. Ann. and Mag. Nat. Hist., 

 London, March, 1867. 



