FISHES OF THE GULF OF MAINE 21 



How far offshore lampreys wander is not known. Probably, however, most of 

 them remain in the coastal zone, if not in estuaries, and there is no evidence that they 

 ever descend to anj^ considerable depth. A few were brought in from Georges and 

 Browns Banks, however, during the early years of the Bureau of Fisheries.'^ 



Since lampreys never take the hook or are captured in nets except on rare occa- 

 sions they are seldom seen in salt water; only when ruiming up our rivers are they 

 familiar objects. 



In Europe, during the middle ages, lampreys were esteemed a great deUcacy — 

 historians tell us Henry I of England died of a surfeit of them — and formerly, 

 when they were much more plentiful than nowadays, considerable numbers were 

 captured in the rivers of New England, particularly in the Connecticut and Merrimac 

 Kivers. They were, indeed, regularly sought in the former until well into the last 

 half of the past century, but for 40 years now the lamprey fishery has been hardly 

 more than a memory except locally and in a small way for home consimiption. In 

 the salt water of the Gulf of Maine the lamprey has never been of any commercial 

 importance; the average fisherman might not see one in a Ufetime, nor is there any 

 sale for the few picked up by chance. 



TRUE FISHES. CLASS PISCES 



Sharks and rays. Subclass Elasmobranchii 



The most obvious external character by which all sharks and rays are dis- 

 tinguishable from the bony fishes is that there are five or more pairs of gill openings 

 on either side of the neck, instead of onty one. In this they agree with the lamprej's, 

 but it is a commonplace that their jaws and teeth are extremely well developed. 

 Their skins are tough and leathery and studded -with denticles (placoid scales), 

 which but remotely suggest orchnary scales and which are not homologous with the 

 scales of bony fishes, for both dermis and epidermis take part in their formation, 

 instead of the former alone. The teeth of the sharks and rays are essentially such 

 placoid scales modified and simply embedded in the gums, not in the jaws. The 

 fins are supported at their bases with segmented cartilaginous rods, and further out 

 by numerous slender horny fibers, instead of by such rays or spines as are to be seen 

 in the bony fishes. All the fins are covered with the same leathery skin that clothes 

 the body. Among sharks the tail is uneven, with the vertebral column extending 

 out into its upper lobe, but in most skates and rays it is whiphke, with no definite 

 caudal fin. The torpedo (p. 6S) is an exception to this rule. 



The skeleton is for the most part cartilaginous, the skull far simpler than it 

 is among the bony fishes, and the gills are attached throughout their lengths to the 

 partitions between the gill openings instead of being free, while the rear portion 

 of the digestive tract is modified into the so-called "spiral valve" by the develop- 

 ment of a special fold from its lining layer. Sharks are usually looked upon as the 

 most primitive of the true fishes. 



" Report of the Commissioner of Fish and Fisheries for 1879 (1882), pp. 811, 812, and 814. Washington. 



