334 PISCES. 



appearance of s^cs produced l)y the union of the faces of the proximate ones. Tlie lahyriiifh of the ear 

 is embedded in the cranium, and tlic nostrils opened by a single orifice, in front of whicli is a blind 

 cavitv, improperly thought a spiracle. The intestine is straight and slender, with a spiral valve. 



Petrom/i:o)}, tlie Lampreys, havp seven gill-openiR^ifs on each side, and the skin on the upper and under parts of 

 tlie tail is formt-il into fln-hke crests, which, however, liaveno rays. The Lampreys properly so called, have strong 

 tei'th in the maxillary rins:, and the inner disc of the lip, which is very circular, is covered with tubercles, hard and 

 crusted like teeth : this rin^ is suspended by a transverse plate answering? to the intermaxillaries, and there are 

 vestig-es of maxillaries on tlie sides. The tongue, whicli moveshackwards and forwards like a piston, and performs 

 the suction, has two lougfitudinal rows of small teeth. Water reaches the frills' from the mouth by a particular 

 membranous canal, a sort of trachea, placed under the g'ullet and perforated with holes ; there Is a dorsal before 

 the vent, and another behind it which unites with the caudal. They habitually fix themselves to stones and other 

 hard substances b)" means of the sucker ; and tliey attach themselves to tlie hir;4est fishes in the same manner, and 

 in the end pierce their intcK'unients and prey upon their substance. 



The species are— P. marlnu.K, the Sea Lamprey, two or three feet long;, marbled with brown and a yellow ground; 

 the first dorsal separate from the second ; two laro;e teeth on the upper part of the maxillary range. In spring; tliey 

 appi'oach the month of livers, and their flrsh is hi^^hly esteemed. P. jluviabilis, the River Lamprey, from a foot to 

 eii;i;hteen inches long ; silvery, with blackish or olive spots on the back ; two larfje teeth in the maxillary ring-; found 

 in the fresh waters. P. plancrii, the Small River Lamprey, is eight or ten inches long, and has the colours and 

 teeth of the preceding : it also inhabits the fresh waters. [The last two are often styled Lamperns.] 



Mlixine. — The members of this genus have but one tooth in the maxillary ring, which is entirely membranous ; 

 two rows of strong teeth on e.Tcb side of the tongue ; but in other respects like the LaniprcNS. The nioutli is 

 circular, with eight cirri, and has a spiracle on the ujiper margin which reaches the interior. The luidy is cylin- 

 drical, and furnished with one fin round the extremity of the tail. The intestine is straight, but simple, and plaited 

 internally, and the liver has two lobes ; no eyes are perceptible. Their eggs grow to a large size ; they discharge 

 ^:o much mucus from the jiores in their lateral line that if kept in a vessel of water they turn it into a jelly; they 

 attack fishes in the same manner as the Lampreys, and they are divided into subgenera according to the number 

 of their gill-oiienings. 



Heptratremiis, has seven on each side, like the Lampreys, and the only known species is from the South Sea. 



GastrobancJiiix, has a common canal to the gills on each side, each of which opens by a hole near the heart, and 

 at one thii d iif the h.'ii-tli Iroiu Ihr head. C. ijlutinosa, the Hag, is the only known species, and i: enters the mouths 

 of fishes wlien (mi tlie rislicrnicn's line, and plunders their substance. 



AinynocttcSy has the entire skeleton so soft and membranous that there is not a bone in the whole, not even a 

 tootli ; they have the external form and gill-openings of the Lampreys, but their fleshy lip forms only a semicircle 

 on the upper part of the mouth, which is furnished with numerous cirri. The known species, A. brancMalis, is 

 from six to eight iiiches long, about the thickness of a goose-quill, and of no use but as bait for other fish. [It has 

 been accused of sucking the gills of other fishes, but perhaps talsely. It is found in the sand and nmd of small 

 streams; preys on worms, insects, and dead matter, and is, in return, preyed on by the Eel.] 



lAinp/iioxtis, has the body compressed, the surface without scales, and both ends pointed. It has a dorsal along 

 the wholpiineof the back, but iio othrr fiii^. The moutb is on the nndrr side of the bodv, opens longitudi- 

 nady, .-iiul has a mw of lilaiurnts on each side. A. hnin-nlalus, the Laricchd. is the only known species. It is a 

 British fish, and an inhabitant of the sea, in which it is found, although ^ery rai-ely, lurking under stones in 

 pools left by the ebbing tide. Pallas considered it as a molluscous animal, and not a fish ; but Mr. Yarrell, in his 

 Brlli.sh Fishes, argues that it is a fish, and tliat in organization it is the lowest of the class. " The form of the 

 fish," says Mr. Yarrell, " is comiiressed ; the head pointed, without any trace of eyes ; the nose rather produced ; 

 the nmnth on the under edge, in the shape of an elongated fissure, the sides of which are flexible ; from the inner 

 margin exN-nd various slender filaments, which cross and intermingle with those on the opposite side. Along 

 the sides of the body the muscles are arranged in regular order, diverging from a central line ; one series passing 

 oljli(|inly upward ;iiid b,ick\Mird, and the nthcr series a^~ obliquely downward and backvard ; t!ie anal apertuie is 

 sitiialcd utir-rourlii nithr length of the lisli in advance of the end of the tail; the tail itsf If pointed ; from the nose 

 to the end of ihe tail, a delicate membranous dorsal fin extends the whole length of th> back, supported by very 

 numerous and minute soft rays; the surface of the body srr.octb." These characteis leave no doubt that the 

 animal is a fisli ; but that it ought to be classed with the Lamprey fandly is am^tlier mfltt'^>*. The specimen from 

 which the description was made was not above an inch in length, very slender, and ainiust transparent.] 



