212 LOWER VERTEBRATES. 



so armed are quite pugnacious, and can protect themselves successfully against most 

 enemies of their size. Three species inhabit the Caribbean Sea, and two of them 

 ascend considerable distances up the Atlantic coast. These are the 7'euthis hepatus, 

 T. coeruleus and T. trachis ; they are more generally known as species of Acanthvrus. 



The SiGANiD^ are confined to the Pacific Ocean, and their homes are in tlie coral 

 regions. The rayed portions of the dorsal and anal fins are equal and opposite each 

 other, and much shorter than the spinous portions. There is a singular uniformity in 

 the number of rays, all liaving thirteen spines and ten rays in the dorsal, and seven 

 spines and nine rays in the anal fin ; the ventrals are quite unique in the development 

 of a spine to the inner as well as outer edges ; the head is short in front of the eyes. 



Between thirty and forty species of Siganidae are known. Some have quite 

 striking colors, disposed generally as spots or blotches. 



The Teuthidoidea are the last of a series which, after a considerable but not impas- 

 sable break, is resumed in forms sufficiently different in aspect, at least, to be generally 

 considered a group of ordinal value, the Plectognathi. Before resuming consider- 

 ation of the important groups, it will be well to notice a couple of small families, both 

 of which have some importance from an economical point of view. 



In the Chesajieake bay, a fish {Elacate Canada) is found, which bears the names 

 bonito and coal-fish, arid, says Mr. Goode, is "considered one of the most important 

 food-fishes of Maryland and Virginia, though it is but little known elsewhere." It is, 

 however, a warm-water fish, and quite widely distributed, and it extends northward 

 from the Caribbean sea. In eastern Florida it is called the sergeant-fish, and along 

 the western coast of the peninsula it is known as the ling or snooks ; it is the cub- 

 by-yew of the Berraudians, a corruption of Cobia, which is a Sjjanish term for it. 

 Crab-eater is a name under which it was early noticed by Dr. Mitchill. Most of the 

 names have been used of old for better-known fishes, and sergeant-fish, or cobia, would 

 be preferable for popular use. The dark stripes which run along the middle of the 

 body have given rise to the name which we prefer to employ. 



The sergeant-fish has been generally approximated to the Scombridje and Caraiigidse, 

 and may be really related to the latter. It is, however, the type of a distinct family — 

 the ELACATiDiE — and is distinguishable by the fusiform shape, smooth scales, lateral 

 line concurrent with the back, depressed head, free spines (eight in nundier) rep- 

 resenting the first dorsal, the long second dorsal and anal, and the acutely lobed 

 caudal fin.. It is quite a large fish, sometimes reaching a length of five feet, and a 

 weight of fifteen to twenty pounds. It is also a ravenous fish, and in Florida was 

 observed by Mr. Clarke " lying under the mangrove bushes in wait for prey, like a 

 pike." A specimen caught near New York had twenty spotted sand-crabs, besides 

 several young flounders, in its stomach, and another caught in Boston harbor consumed 

 all the fishes in the 'car' in which it w:is ])Iari'(l. The sergeant-fish is known to breed 

 in Chesapeake bay. 



Another small family, peculiar to the tropical and subtropical waters of America, is 

 that called CENTEOPOSiiDyE. These have an elongate body, small ctenoid scales, a very 

 distinct lateral line continued on the tail, well-separated dorsals, the first with seven 

 or eight spines (of which the third is the longest), a short anal with three spines (the 

 second is much the strongest), and a forked caudal. The most salient peculiarities, 

 however, are to be seen in the skeleton, and especially the posterior part of the skull. 



In the English West Indian colonies the species of Centroponms are generally called 

 snook, and in the Spanish robalo. The earliest known is the C. undeci)nalis, which 



