152 



ICHTHYOLOGY. 



Introduc- saw and examined for tliemselves, and made drawings from 

 tion. nature, if not with the elegant accuracy of modern days, at 



^'^~y-^ least with a recognisable exactness. Yet, true to the ge- 

 nius of their time, they continued to attach much more 

 importance to the ascertainment of the names which the 

 species bore in the classical pages of anticjuity, than to the 

 composition of th.eir history, as it were afresh, by the light 

 of nature and their own knowledge. Nevertheless they 

 rectified as well as extended the observations of Aristotle, 

 and laid a positive base or new foundation of the subject, 

 by figures and descriptions of a certain number of well-de- 

 termined species. About the close of the seventeenth cen- 

 tury, Willughby, and his illustrious friend John Ray, gave 

 tor the first time a history of fishes, in which the species 

 were not only clearly described from nature, but distribut- 

 ed in accordance with characters drawn solely from their 

 structure, and in which we are no longer unnecessarily 

 burdened with inapplicable passages from either Greek or 

 Roman writers. Finally, about the middle of the eigh- 

 teenth century, Artedi and Linnreus completed what the 

 others had commenced, by establishing well-defined generic 

 groups, consisting of ascertained species precisely charac- 

 terised. From that period it may be said that no radical 

 defect existed, nor any obstacle in the way of a gradual 

 perfecting of the system, which could not be overcome by 

 zeal, accuracy, and perseverance. Nevertheless it is to the 

 genius of Baron Cuvier that we owe the gigantic stride 

 which has been made in our own more immediate days. 

 Prior to 1815, the methods of almost all the modern syste- 

 matic writers were little else than modifications, variously 

 disguised, of the Linnaean system, — that is, with alterations, 

 generally for the worse, of the nomenclature of the illus- 

 trious Swede. They darkened knowledge by a multipli- 

 city of vain words ; — and when any principle of classifica- 

 tion was brought forward, — if new, then it was untrue to 

 nature, — if true to that beautiful abstraction, then it was 

 already familiar as household words. But forty years assi- 

 duously devoted to Ichthyology, — that is, to a deep study 

 of all preceding authors, to a constant ascertainment of 

 whatever could be gathered of the habits of fishes, and to 

 the formation of an unrivalled museimi of comparative ana- 

 tomy, where both their outward and internal forms were 

 perfectly displayed, — convinced tlie great French naturalist 

 that many heterogeneous groups still formed portions of 

 our ichthyological system, and that a salutary reformation 

 might consequently be effected in numerous minor details. 

 It was obvious, from an attentive consideration of the 

 subject, that the differences of both external and interior 

 organs, by which fishes might be distinctly characterised, 

 were not less numerous than decided ; and that in truth 

 there were few classes of created beings among which it 

 was more easy to recognise the existence of natural groups. 

 But with a view to dispose of the genera and families in a 

 becoming order, it was necessary to seize upon a small 

 number of important characters, from which might result 

 certain great divisions, not likely to break up nat>u-al rela- 

 tions, and yet sufficiently precise and perceptible to leave 

 no doubt as to the place of each species. This was a prin- 

 cipal desideratimi, and one which the industry and perse- 

 verance, not less than the genius and high attainments, of 

 Cuvier, have gone so far to satisfy. 



The numerous characters lield in common by the chon- 

 dropterygian or cartilaginous fishes were too remarkable to 

 have escaped detection by those who loved and sought for 

 the light of system. Thus all Ichthyologists have agreed 

 in the formation for these fishes of a separate order ; but 



the Baron has observed, that almost all have likewise in- Introduc- 

 jured the justness of their ordinal division, by a combina- ^'^""■ 

 tion of certain species which resembled the true cartila- ^■"^"^^ 

 ginous kinds merely in the softness of their skeleton. Thus 

 the genera Lophius and Cyclopterus, except in that soft- 

 ness, do not differ in any respect from tlie ordinary osseous 

 fishes, and therefore ought not to be withdrawn from them. 

 But there are others which, in addition to the softness of 

 their bones, present peculiar characters in their tegumen- 

 tary system, in their teeth, and especially in the disposition 

 of the skeleton of the head, which render their immediate 

 imion with either of the great groups of osseous or carti- 

 laginous fishes a matter of greater doubt and difficulty. 

 Such, for example, are the genera Tetrodon, Diodon, Os- 

 tracion, and Batistes. The Syngnathi, or pipe-fish, like- 

 wise present, in their peculiar branchia?, distinctive charac- 

 ters of great importance. The remarkable external aspect 

 of these different genera had long induced the majority of 

 naturalists to separate them from the others ; but it so 

 happened also that the same majority were by no means 

 fortunate in discovering the true characters of separation. 

 Thus Artedi not only re-united them to the Loptiii and 

 lum)>fish, in the order of branchiostegous fishes, but he 

 established that entire order on a false supposition — to wit, 

 that they possessed no rays in their branchial membrane 

 (" biaNc/iiis osseis, ossibus destilutis," — " t)ranchiostegi in 

 branchiis mdta ossicula germit,"^) — while the fact is, that 

 they all possess those rays, and that even Artedi himself has 

 inadvertently described both their nature and their number 

 (^membrana branch iostega ossicuta sex gracilia conti?tet) in 

 his notice of the lump-fish [Cycloptey'us) in question.^ 



Linna;us,^ after placing the chondropterygian fishes 

 among the reptiles, and adding thereto the genus Lo- 

 p/iius ; after referring the Mormyri and Syngnathi to the 

 branchiostegous fishes of Artedi, and assigning to them 

 the character of wanting not only the rays of the branchiae, 

 but the opercula (the contrary in several species being ob- 

 vious to the most simple observation) ; afterwards combin- 

 ed'' the Chondropterygii and Branchiostegi into a single or- 

 der oi reptiles (^Amphibia Nantes), on the supposed but quite 

 erroneous basis of their being possessed at once of lungs 

 and gills. Gmelin re-established the two orders of Artedi, 

 but still attributing to the Branchiostegi the absence of 

 rays. Gouan characterised them merely by the incom- 

 pleteness of their branchia:, — a vague expression, and in- 

 deed contestable in almost all the genera. Pennant com- 

 bined them with the Chondropterygii, imder the common 

 name of Cartitaginous, a term adopted by M. Lacepede ; 

 but which Cuvier has shown, in relation to the actual con- 

 tents of the grovip, to be improper. The great French ana- 

 tomist has observed that the appellation is by no means 

 applicable, either in a positive or a negative sense. It can- 

 not in any way be maintained that the skeleton of the Ba- 

 tistes is cartilaginous ; and among the number of species " 

 which Pennant and his followers leave among the osseous 

 fishes, there are several, for example, the Leptocephali, in 

 which we can scarcely perceive the vestige of a skeleton.* 

 Baron Cuvier"s great object thus became, to disentangle, 

 as it were, those anomalous groups, or at least to separate 

 all such as seemed to differ sufficiently from the type of 

 ordinary fishes to authorize such separation. His next 

 object was the discovery of precise characters, cajiable of 

 being clearly expressed in words. This examination soon 

 convinced him that such genera as Lophius, Cyclopterus, 

 Centriscus, Mormyrus, and Macrorhynclms, had been er- 

 roneously withdrawn from the great group of ordinary 



' Genera Piscutm, p. 85. 



= Ihld. p. (i2. 



^ Sf^stCfua Nitiurtr, 10th ed. 



* Syitema Nalura, 12th ed. 



» Hist. Nat. des Poissons, t. i. p. 555. 



