ICHTHYOLOGY. 



249 



otherwise associate. Tliey are fresh-«ater fishes, interest- 

 ing to ichthyologists from their characters, but ot" no great 

 importance to man. The Hyodons, from which tlie group 

 derives its appellation, are small fishes of North America, 

 known locally by the name of Gold Eye, and having a re- 

 semblance to the Trouts in feeding on insects and taking 

 the artificial fly freely. They, as well as Osleoglossum, are 

 among the fishes which have the interior of the mouth most 

 fully armed, since they possess strong teeth far back on the 

 palate as well as on the tongue and jaws. 



Family VIII.— HYODONTID^. 



HyodonUs, Valenc. M. Valenciennes places in this group Osteo- 

 glossum^ Jschnosoma, and Hyodon, which liave compressed bodies, 

 and a keeled belly, without denticulations, but with pancreatic 

 ca^ca, the presence of which, he says, alone separates them for 

 Chirocentrns, though the suborbitar scale bones are more developed 

 than in the latter. Their intestinal canal resembles that of the 

 Mormyri. 



Gends I. OsTEOGLOSSnM, Fereira. Body and head compressed 

 like the blade of a sabre ; head bony above, and tiie cheeks pro- 

 tected by the suborbitars and opercular pieces ; mouth much cleft; 

 small conical teeth on the premaxillaries and slender maxillaries, 

 which move little, and are partially concealed by the preorbitar ; 

 lower jaw armed like the upper one with two fleshy barbels under 

 the symphysis; minute crowded teeth cover the vomer, the pala- 

 tines, entopterygoids, presphenoid, lingual bone, and body of the 

 hyoid bone. Gill-openings very large, overlaid by the wide mem- 

 branous border of the gill-cover ; branchiostegals ten. Anal long, 

 but separated from the small caudal ; ventrals ending in a filament- 

 ous point. Belly trenchant, but without denticulations ; stomach 

 rounded, without any caecal projection ; two pancreatic caeca ; air- 

 bladder large, simple, without either partitions or horn-like pro- 

 longations, but communicating with the upper part of the oesopha- 

 gus by a tube having an excessively small mouth. Two species, one 

 in the Amazon, the other in Borneo, 



Gends II, Ischnosoma, Spix. An Osteoglossum, with the anal 

 and caudal united. . 



Ge.nus III, Hyodon, Lesu,, Rafin. Body scaly, greatly com- 

 pressed, thickest above the lateral line ; back acute, belly more 

 so; profile suboval. Dorsal short, over the long anal. Eye large, pre- 

 orbitar scale bones covering the whole of the cheek ; mouth wide, 

 premaxillaries and maxillaries forming equal portions of its upper 

 border. These bones have uniserial conical teeth, largest towards 

 the symphysis ; the mandible has two rows with their points in- 

 clined backwards, and the interval between the rows covered with 

 minute teeth ; the vomer is similarly armed, but the dental surface 

 widens gradually as it approaches the gullet ; the palatines are 

 armed by a single row of conical teeth, with a small oval plate of 

 very minute ones within the middle of the row ; tongue strongly 

 armed by a marginal row of hooked teeth bigger than the others, 

 anfl the rest of the surface covered with minute card-like teeth, 

 having their points rellexed. Stomach siphonal ; one pancreatic 

 caecum ; air-bladder large, communicating with the oesophagus. 

 Fresh-water North American fish. 



CLUPESOCIDvE. 



This family was indicated by Miiller in his treatise on the 

 Natural Familiesof Fish, and was considered by him to be dis- 

 tinct from the true Herrings by having no pseudobranchise, 

 which the Clupeoids all possess. On subsequently examin- 

 ing some examples of the genus Megalops, he found the 

 pseudobranchiae present, though evanescently small; and he 

 also discovered that Gnalhobolus, a genus closely related to 

 Notopterus, has pectinated pseudobranchia;. He therefore 

 ceased to consider the Clupesocida as a separate family, 

 and referring them all to the Clupeida, enumerates as mem- 

 bers of that family, Clupea, Pristigaster, Alepocepluilus, 

 Gnatlxoholus, Notopterus, Engraulis, T/iri/ssa, 3Iegaloj)S, 

 Etops, Lntodeira, hyodon, Butirinns, Cliirorentnts, Sto- 

 mias, Chauliodus, Heterotis, Arapaima and Osteoglossum. 

 Neither Ainia nor Chauliodus have pseudobrancliia;. M. 

 Valenciennes has treated of the genera here enumerated as 

 intermediate between the Clupeida; and Esoculte, and con- 

 siders several of them to be types of distinct liimilies, some 



VOL. XII. 



lacopteri. 



of which have been named by him. After abstracting these, Classifica- 

 theremainder are hereplaced under the head of Clupesocidce, "°" " 

 as a convenient term indicating their position between the 

 natural families of the Herrings and Pikes. When their 

 anatomy has been more perfectly investigated, they will be 

 distributed by ichthyologists to their proper places in the 

 system. One |)art of the structure of a fish is much attended 

 to by Miiller in his searches after the nat\iral affinities of the 

 various genera he examines, viz., the investments of the 

 ovaries, or the organs which hold the roe or eggs. In the 

 Salmon tribe the eggs are not contained in a separate sac, 

 but drop off from the ovary as they come to maturity, into 

 the general cavity of the abdomen, and are expelled from 

 thence ; in the Ga/axidee and in various groups that have 

 been separateil from the S'almoiiidfB, the ovaries are inclosed 

 in a sac, which has a canal of its own, through which the eggs 

 pass in the process of spawning. A too rigid adherence to a 

 single chai'acter often separates fish that are connected by 

 many natural affinities; and some of the ClupesoridcB v/ou\d 

 associate well with the Scopelida did they possess an adi- 

 pose dorsal ; tlie absence or presence of teeth on the palate 

 has also been occasionally made of too much importance by 

 systematists. 



The genus Notopterus is peculiarly interesting to syste- 

 matic naturalists on account of the combination of charac- 

 ters of very different orders of fish which it presents. With 

 the compressed body of a Clupeoid, it has the denticula- 

 tions of the preorbitars, suboperculum, and mandible, and 

 the cranial crests observed in several fixmilies of Acanthop- 

 teri, together with a Gobioid union of the ventrals, in which 

 also it agrees with Gonorliynchus ; the dentition, especially 

 the existence of spheroidal teeth, allies it to Butiriwis, while 

 the armature of the tongue brings it near to the Hyodontidce 

 or to Mormi/rus. The eggs are not shut up in a sac, but 

 fall freely into the abdominal cavity as in the SalmonidcB. 



The genus Arapaima, so named by Miiller, and since 

 called Vastres by Valenciennes, was termed Sudis by Cu- 

 vier ; but Rafinesque having previously used the word Sudis 

 to denote a fish of a totally different kind, the name has been 

 necessarily dropt as an appellation of this genus. The spe- 

 cies are of much interest not only from the peculiarities of 

 structure which they exhibit, and their encasement in strong, 

 bony, compoimd scales, but from the great size which they 

 attain, exceeding that of almost all other fresh-water fishes, and 

 also fiom the excellence of their flesh as an article of food. 

 Sir K. Schomburgk mentions, that in the Rio Negro some 

 are taken which measure fifteen feet in length, and weigh 

 four hundredweight. They are harpooned, or taken with 

 a baited hook, and are the objects of considerable fisheries. 

 They fetch a high price, and are excellent when fresh, espe- 

 cially the belly part which is very fat. When salted they 

 are exported in large quantities to Para, and are there 

 preferred to the salted fish from the banks of Newfoimd- 

 land. 



Butirinus and Heterotis are also interesting, but more 

 from peculiarities of their structure than from their utility to 

 man, though, as articles of food they rank among the more 

 highly prized fishes. 



Family IX.— CLUPESOCIDiE, MuU. 



No adipose fin ; no accessory gills ; premaxillaries bounding the 

 orifice of the mouth in the middle above, and the maxillaries the 

 sides. Some have a simple swim-bladder ; pyloric caeca in a few, 

 in others absent. Distinguished from the Clupeidce by the ab- 

 sence of accessory gills. They include the following genera: 

 Stomias, Ckirocentrus, Nutoplcrits, Osteoglossum, Heterotis, and Sudis, 

 Cuv, (or Arap'aima, Miill.) 



These genera were either associated with Hfox by M, Valen- 

 ciennes, or considered as type,^ of peculiar families ; and at a later 

 period Muller ceased to consider these fish as forming a proper 

 family, but we have placed them togetlier until appropriate posi- 

 tions are found for them, 



2i 



