ICHTHYOLOGY. 



089 



C**na * ed even those fish which live in the sea, as the follow- 

 ing fact, communicated by the late Mr Creech of Edin- 

 burgh, in the Appendix to the sixth volume of the Sta- 

 ti-ttcal Account of Scotland, satisfactorily proves: " On 

 Friday, 4th December ITff), the Ship' Brothers, Cap- 

 tain Stewart, arrived at Leith from Archangel. The 

 captain reported, that on the coast of Lapland and 

 Norway he sailed many leagues through immense quan- 

 tities of dead haddocks floating in the sea. He spoke 

 several English ships, who reported the same fact." 



Fishes are greatly tormented with intestinal worms. 

 The common stickeback may be quoted as a remarka- 

 ble instance. Its death is often occasioned by the in- 

 crease of the Ttfttia tolida of (hnelin ; and it is even 

 supposed, that the extinction of its existence by this pa- 

 rasite follows the function of reproduction with regu- 

 larity. A*naU of Philosophy, February 1816. 



Fishes exhibit remarkable differences with respect to 

 their vii-aciousnett. Thus some fishes expire almost the 

 instant they are taken out of the water, as the herring, 

 the smelt, &c. Others are capable of surviving hours 

 and even days, when removed from their native ele- 

 ment, as the eel, carp, and some others. It sometimes 

 happens that vivacious fishes are conveyed to a distance 

 by birds, and left, without being killed, on rocks or 

 fields. This has given rise to many of the absurd sto- 

 ries which have been told of showers of fishes. Ron- 

 deletius observes with propriety, that those fishes whose 

 gill openings are but imperfectly covered expire ioPest 

 when taken from the water; and those fish whose 

 branchia are protected by a gill-lid which shuts dose, 

 or by a narrow opening, are most vivacious. The air 

 soon drie* the fine plumes of the branchiir. and olv 

 struct* the process of respiration and of circulation. 



Few accurate observations have been made to deter- 

 mine the off of fishes. The element in which they re- 

 side is supposed to preserve them from the pernicious 

 influence of sudden change* of temperature ; the slow- 

 ness of the process of ossification ; the coldness of their 

 blood ; and the tardiness of all their primary move- 

 ments, are considered as indicating a lengthened ex- 

 istence. Accordingly we find, the age of the carp has 

 been known to reach to 200 years, and the pike to 260. 

 The marks by which the age of fiahes may be deter- 

 mined, have never been pointed out in a satisfactory 

 manner. As the age of trees may be guessed at by the 

 number of concentric circles in the wood, so it has been 

 supposed that the age of fishes may be ascertained by 

 the number of concentric circle* in the scales or in the 

 vertebra-. Such analogical reasonings are hurtful to 

 science, as they occupy the place of observation. They 

 have done so in this instance at least 



It is seldom that a fish is permitted to die a natural 

 death, from old age. During every period of it* exist- 

 ence it 11 surrounded by fos* : and when no lunger able 

 to exercise hs wonted watchfulness, or exert its powers 

 of defence, it falls an easy prey to it* more powerful ad- 

 versaries. In a domesticated itate, previous to death, 

 the dorsal fin* lose the power of maintaining the body 

 in a vertical position, the levity of the belly, and the ex- 

 traordinary distension of the air bag, reverse the natur.il 

 position, so that the back becomes undermost, and the 

 animal floats on the surface. Similar appearances pre- 

 sent themselves, when the waters are contaminated by 

 noxious mineral or vegetable impregnation*. 



ftsnlfck. 



SECT. VII. Fo*nir,,k. 

 The investigation of those changes which have taken 



VOL. XI. FAIT \'.. 



place in the race of fishes since the formation of the 

 globe, is attended with peculiar difficulty. The exter- 

 nal form, on which in general the specific distinction is 

 founded, is destroyed by pressure. All distinct traces 

 of the softer parts have disappeared, and the geognost 

 is loft to draw his conclusions from the form of the teeth, 

 or the outline and structure of the skeleton. Hence the 

 conclusions which have been drawn respecting the par- 

 ticular species should be received with caution. In the 

 newer rock formations, which have been termed local, 

 such as the strata at Eningen, the remains of fishes have 

 been observed, belonging to existing races, and still na- 

 tives of the neighbouring lakes. But in the rocks of 

 those formations which are called universal, the skeletons 

 of fishes which have been found, in all probability be- 

 long to species now extinct. In examining the organic 

 remains which we consider of this sort, it would appeal- 

 that the teeth of unknown sharks are more numerous 

 than Uhose of any other description of fish. They art- 

 found in all the noetz limestones of this country, m 

 company with the ancient camerated shells. Vertebra: 

 of osseous fishes are chiefly found in the strata con- 

 nected with the chalk formation, seldom in those of an 

 older date. 



Before concluding this chapter, it may not be unac- 

 ceptable to the reader to be presented with a few ob- 

 servations on the preservation offshes for a museum. 



The simplest method consists in dividing the fish Method of 

 vertically and longitudinally, taking care to preserve j? 

 attached to one side the anal, dorsal, and caudal fins. mueum> 

 From this side the flesh is then to be scraped off, the 

 bones of the head reduced in size, the base of the fins 

 in.ule thinner, and the specimen then stretched out on 

 pasteboard and dried. By this means a lateral view of 

 the fish is preserved, and if the fins and gill-flap are 

 cautiously spread out, the specimen will furnish suffi- 

 cient marks for recognising the species. A collection 

 of such fishes may be kept in a portfolio, similar to an 

 herbarium. 



Many species may be well preserved, by extraotinp 

 the contents of the body at the mouth, or skinning the 

 fuh with the skin entire from the mouth towards the 

 tail, in the same way as eels are prepared for cooking. 

 Let it then be restored to its former position, fill tin- 

 whole with fine sand, and having spread out the fins, 

 let it be dried with care. Almost all wide-mouthed cy- 

 lindrical or tapering fishes may be preserved in this 

 manner. Some recommend filling the skin with plaster 

 of Paris, while others employ cotton. Preserved fishes 

 are usually covered with a coat of varnish, to restore in 

 part the original lustre. But no means of this sort can 

 retain many of the brilliant colours which the animals 

 of this das* posse** ; and even the form of some of the 

 soft parts cannot be preserved. Hence fishes are in ge- 

 neral preserved in bottles of spirits of wine. In this 

 way, it is true, they take up much room, but they can 

 be subjected to examination at pleasure, and all their 

 characters satisfactorily exhibited. 



CHAP. IV. 



CLASSIFICATION or FISHES. 



IN the last chapter, when treating of the structure C 

 and function of fishes, we endeavoured to point out the |j" ot 

 relative value of those characters which systematic 

 ichthyologists have hitherto employed. We there gave 



