ICHTHYOLOGY. 



263 



Classifica- * spine running along the whole back ; its posterior half sometimes 



^j^jj jia. rei)laced by an adipose tin. Pectoral spine small. Branching ap- 



lacopteri. pendages for holding water attached above the branchiae ; air- 

 ^ ; bladder divided. Fourteen species. 



■^ GENfS XXXIV. IlETEKOBUANCiIUS, Geoff. Dorsal shorter than 



in Clarias, the rest of the back being occupied by an adipose fin ; 

 caudal rounded. Head broad and flat ; supraoccipital process of 

 the helmet rounded. Short, fine, crowded villiforni or bristle-like 

 teeth on the jaws and arc of the vomer ; a complex suprabranchial 

 apparatus. Si.x barbels. Three species. 



Genus XXXV. SaCCOER.\ncuus, Valenc. Helmet like Clarias 

 and Hi'terobranchus. ViUiform teeth on the jaws, and two arched 

 dental plates on the vomer ; a complex suprabranchial apparatus. 

 Small dorsal far forward; long anal. Seven branchiostegals ; 

 the branchial reservoir different in form from that of Clarias ovHete^ 

 robranchus. Eight barbels. One species. 



Genus XXXVI. Plotosus, Lacep. An elongated body, ending 

 in a compressed pointed tail. No hard helmet, the smooth rounded 

 depressed skull being covered with soft skin. Lips fleshy ; strong 

 conical teeth on the jaws ; pavement-like teeth on the vomer ; eight 

 barbels. A short, higher, anterior dorsal, and a long, low, posterior 

 one, uniting with the long anal at the point of the tail, without a 

 distinct caudal. Small trenchant, toothed and pointed dorsal and 

 anal spines ; a cauliflower-shaped tubercle in a funnel behind the 

 anus, of unknown use, existing in addition to the genital tubercle at 

 the external opening of the seminal deferent canal. Nine species. 

 Genus XXXVII. Aspredo, Linn. Differ from other fish in the 

 gill-covers being fixed and without motion, there being merely 

 vestiges of the three opercular pieces, soldered to the preoperculum. 

 Mouth peculiar, the premaxillaries being articulated longitudi- 

 nally under the snout, and carrying teeth on their posterior edge 

 only ; and the maxillaries ending in bai'bels, articulated to the nasal 

 anterior to the premaxillaries. Head flat, anteriorly. Body naked, 

 wide at the pectoral region, tapering into a long slender tail, tren- 

 chant beneath, and terminated by a distinct small caudal. Dorsal 

 small, high ; strong, flat, serr.ated pectoral spines ; anal long ; no 

 adipose fin ; cup-shaped suckers on the ventral surface at certain 

 titnes. Branchiostegals five. Si.x species, all American. M'Clel- 

 land describes five Indian fish belonging to a genus named Gliip- 

 tosUrnon, which does not seem to differ from Aspredo in the cha- 

 racters that he assigns to it. 



Ge.xus XXXyill. C'HACA, Valenc. Head broad and much de- 

 pressed, as wide before as behind, thus being quadrangular ; tail ta- 

 pering and much compressed at the end. Two dorsals and two anals ; 

 posterior ones uniting to form a caudal at the extremity of the tail, 

 or it may be said, caudal running forward on tlie dorsal aspect to 

 above the front of the anal, and about half as far on the ventral 

 aspect, in which point of view there would be one anal and one dorsal 

 near the head, supported by a strong osseous first raj^ Serrated pec- 

 toral spines. The chin cirrhated by eight filaments. Air-bladder 

 very large, composed of two lobes separated by the spinal column. 

 Genus XXXIX. Sisor, Hamilt. Buch. A Huposiomus without 

 lateral pieces of mail, its skin being soft ; remarkable for the size 

 of its premaxillary barbels, and the prolongation of the upper 

 caudal ray into a filament as long as the rest of the fish. Body 

 Blender, long ; the chevron in front of the dorsal three-lobed. Mouth 

 edentate, with fourteen barbels in all. Large gill-openings; four 

 branchiostegals. One species, which attains the length of seven feet. 

 Genus XL. SIalaptekurus, Lacep. No anterior dorsal ; an 

 adipose fin near the caudal ; ventrals beyond tiie middle of the fish ; 

 and an anal occupying about half the distance between them and 

 the rounded caudal ; no pectoral spine. Body shaped somewhat 

 like that of a Cobitis or Galaxias^ the tail being thickish, but the 

 head is conical and ends bluntly. Lips fleshy, with six barbels ; 

 fine villiform teeth on each jaw ; none on the vomer. A short ob- 

 lique gill -opening ; branchiostegals seven. Stomach small, siphonal ; 

 air-bladder fusiform, pointed posteriorly with two globular lobea 

 in front, in advance of the ossicles of Weber. Its outer coat is 

 thick and spongy. A double electrical organ. 



Genus XLI. Ailia, Gray. A long, greatly compressed, mode- 

 rately high fish, with a small head and rounded snout like a Schilbes. 

 Back naked, except near the tail, where there is a small adipose 

 fin ; a very long, even anal, and forked caudal. Eight barbels. 

 Teeth on the jaws and roof of the mouth minute. 



Genus XLII. Trichomycterus, Valenc. Allied io Malapte- 

 rurus by general form, the depression of the head, thinning of the 

 snout, and construction of the cranium, but distinguished by a 

 dorsal placed in the middle of the back, the absence of an adipose 

 fin, and the want of an air-bladder. Branchiostegals eight. Aspect 

 considerably like that of Cobicis. Six barbels, one at each anterior 

 nostril, and a pair at the corner of the mouth on each side. Tail 

 thickish. Fine curved teeth in a band on the jaws ; palate smoothed. 

 Three species. 



Genus XLIII. Eremopiiilus, Humb. Closely resembling 



Trichomycterus in general aspect, but apodal ; connected like that Classifica- 



genus to the Siluroids by the absence of subopercula ; and to Cobitis tion — Ma- 



by the want of ventrals. Jaws armed by a band of long villiform or lacopteri, 



bristle-like teeth. Branchiostegals eight; no scales. Siphonal ^ ],- '-' 

 stomach and long intestine ; no air-bladder. 



GONIODONTS. 



This family has grown out of the genus Loricaria of 

 Linnaeus, which, as characterized by him, consisted of 

 fislies wliose bodies were mailed in hard angular |)lates or 

 scales, distinguished from Doras and Callichtliys by the 

 movith opening under the snout. Miiller considers them to 

 be a separate group of the Siluroid family, and as such they 

 are described by Valenciennes, in the Histoire des Poissons. 

 Lace|)ede divided the Linnaean Loricaria into two groups, 

 reserving that appellation (or the species that have no adi- 

 pose fin, and giving the name of Hypostoma to those that 

 have a kind of adipose fin but one tliat is preceded by a 

 hard bony ray. Agassiz, when characterizing and naming 

 the family, ado|)ted Lacepede's generic divisions, and added 

 t« o others, Rhinelepis and Acanthicus. The premaxillary 

 and mandibular teeth of the Goniodonts are composed of 

 albuminous tissue, like the teeth of the Chaetodons, and have 

 the same elasticity. 



In the LoricaricB the top of the skull is prolonged back- 

 wards by the extension of the supraoccipital, which forms a 

 kind of first scale, that reaches to the two plates developed 

 from the points of the interneurals of the first compound 

 vertebra, — the second of the plates being the chevron, on 

 which the spine of the dorsal stands and moves. The mas- 

 toids and suprascapulae enlarge the sides of the skull, and 

 form the wide osseous vault, which affords the necessary 

 space and breadth for containing the anterior portion of the 

 abdominal viscera. The diapophyses of the great compound 

 vertebra are plates curved like a sabre, and are sup|)orted 

 below by the centra, and above by a styloid process resting 

 on the vertical occipital crest. The scapular arch is very 

 strong and shuts up the fore-part of the abdomen by a 

 bony septum, while the coracoids, in form of the letter V, 

 give the firmness necessary to sustain the dermal shields 

 and spines. The coalescent radius and ulna bent horizon- 

 tally support the pectoral plates. There are only eight 

 abdominal vertebrae, with ribs as fine as bristles, and sixteen 

 caudal ones. 



Family XIX.— GONIODONTID^. 



Ooniodontei, Agass. ; Loricarini, aliorum. Related to the Silurida, 

 but differing from them in possessing pseudobranchiae, and in 

 their intestines. Head and body mailed in hard, angular plates; 

 orifice of the mouth on the ventral aspect under the snout, and 

 bounded by the premaxillaries and maxillaries ; long, slender, flexi- 

 ble teeth ending in hooks on the premaxillaries and mandible, 

 which are separated at the symphysis; a broad, circular, cuticular 

 fold surrounds the mouth. Gill-cover mostly immoveable ; the sty- 

 loid epicoracoid absent as in the Siluridw, and represented by a 

 process of the coracoid. The heart lodges in a bony capsule formed 

 by the coracoid. No caical enlargement of the stomach ; intestine 

 long, frequently bent ; no pancreatic caeca. Swim-bladder want- 

 ing, in which they differ from the Siluridce. There is much phos- 

 phate of lime in the scales. 



Genus I. Loricaria, auct. Body depressed, broader than 

 high. Tail very much compressed. Teeth in both jaws. A single 

 dorsal and no adipose fin. 



Genus II. Hemiodon, Knor. Body very much depressed. 

 Teeth on the mandible only. Premaxillaries rudimentary ; tooth- 

 less. 



Genus III. Acestba, Knor. Body elongated, nearly cylindri- 

 cal. Teeth in both jaws, furnished with a tranverse radical process. 

 Dorsal and anal fins opposite. 



Genus IV. Rhinelepis, Agass. Osseous plates resembling 

 scales, imbricated, rough like a file. A short thick body. Lower 

 lip often dilated into a membranous velum, and fringed with 

 filaments. Three branchiostegals. Hooked teeth surrounding the 

 orifice of the mouth in rows ; the front ones notched at the point, 

 A single dorsal. Three species. 



