328 



ICHTHYOLOGY. 



Classifica- 

 tion — 

 Rays. 



Genus III. Pteroplatea, Miill. and Henle. Disk nearly twice 

 as broad as it is long. Tail for the most part shorter than the 

 body, bearing one or more spines, with low cuticular seams, or quite 

 naked. Mouth crescentic, with the dental plate reaching to its 

 corners. Teeth having from one to three cusps; upper velum not 

 fringed ; no papilla? behind the under teeth. Skin smooth or tu- 

 berculated. Three species. 



Genus IV. T.eniura, Mull, and Henle. Disk roundish. Tail little 

 longer than the body, depressed before the spine, which is near its 

 middle, compressed posteriorly, with a high under-fin running from 

 Dear the spine to the end, together with a shorter or longer cuti- 

 cular hem above, also reaching the point. Nostrils approximating 

 as in Tryiion. Teeth with a transverse ridgs or a cusp. Alouth 

 straight or undulated. Upper velum straight. No papillse below. 

 Five species. 



Genus V. Uuolophus, Miill. and Henle. Disk roundish, egg- 

 6baped or rhomboidal. Tail destitute of a dorsal, but with a cau- 

 dal which has cartilaginous rays, and reaches further forwards 

 below than above. Teeth and mouth as in Truijon ; upper velum 

 gently scalloped ; under one with five warts. Four species. 



Genus VI. Trygonoptera, Jliill. and Henle. Tail short, broader 

 at the end, with a small rayed dorsal immediately before the spine. 

 Teeth rather acute. Disk as in Trygon. One species. 



Genus VII. Aetoplatea, Valenciennes. A Pteroplatea, except 

 that it has a dorsal before the spine. One species. 



Family VI.— MYLIOBATID^. 



Head more elevated than in Rata, projecting as far as the gills, 

 beyond the pectoral disk, having no fin-rays on its sides, but a kind 

 of head fin is developed before the skull, making the point of the 

 disk. Nasal flaps forming the sides of a quadrangular flap which 

 reaches to the mouth, and is fringed posteriorly ; nostrils sepa- 

 rated by a thin fillet merely, which comes from both angles of the 

 mouth over the quadrangular flap, and is slightly pointed in tlie 

 middle. Mouth transverse ; dental plates reaching far back in the 

 cavity of the mouth. Teeth large like mosaic pavement, even ; 

 upper velum very long, with a conve.^ border fringed in the mid- 

 dle ; under velum close to the teeth, with only one papilla behind. 

 Eyes and spout-holes in the sides of the skull ; a broad bridge 

 between the spout-holes and eyes. No eyelids. Tail long, whip- 

 like ; a dorsal fin on its root, and a spine behind the dorsal. 



Genus I. Myliobates, Cuv. (Aetobates, Blain.) Union of the 

 antecephalic rays of the pectoral forming a pointed snout; nasal 

 flaps joined by a straight-edged membrane. Mouth transverse. 

 Teeth arranged in a mosaic pavement of long he.\agonal plates in 

 the middle, and two or three I'ows of short quadrangular or hexa- 

 gonal pieces on the sides ; on the upper jaw the dental surface is 

 convex both longitudinally and transversely. Five species. 



Genus II. AETObATES, Miill. and Henle. Snout pointed, not 

 notched ; under edge of the coalescent nasal flaps deeply notched ; 

 the nasal bridle pa])illose. Upper jaw straight-edged ; crowns of 

 the teeth in rows ; the dental plates not extending to the sides of 

 the jaws. Two species. 



Genus III. Khinoptera, Kuhl. Snout deeply notched in the 

 middle. The antecephalic fin in a lower plane to that of the pec- 

 toral, and joined to the inferior base of the latter. Nasal flap straight 

 posteriorly ; its lateral angles pointed. Jaws straight ; teeth occu- 

 pying the whole transverse breadth of the jaw, and forming from 

 three to five rows of transversely long, antero-posterior narrow hex- 

 agonal plates, with smaller lateral ones as wide as they are long. 

 Six species. 



Family VII.— CEPHALOPTERID^. 



Head straight transversely in front. The precephalic fine pro- 

 ceed from the under edge of the pectorals, and project like ears on 

 the sides of the head, and curl upwards and inwards. Under edge 

 of the coalescent nasal flap straight ; nostrils near the precephalic 

 fins, wide laterally. Teeth very small. Eyes on the sides of the 

 skull immediately before the commencement of the pectorals. Spout- 

 holes on the dorsal aspect, widely separated from the eyes. Tail 

 as iong, or longer than the body, bearing a dorsal fin, and behind it 

 a spine. 



Genus I. Cephaloptera, Dum. {Dicerobatis, Rlain.) Mouth 

 on the ventral aspect. Teeth of both jaws small, flat, pavement- 

 like, of diverse forms. Pectoral fin prolonged forwards to a point 

 beyond the truncated head, looking like a horn; the edge of the 

 fin from this point to behind the eyes being convex. Four species. 



Genus II. Ceratoptera, Mull, and Henle. Mouth at the end 

 of the snout ; upper jaw crescentic on the edge ; under one convex ; 

 no teeth in the u|)per jaw ; on the under jaw they are small and 

 scale-like. Pectorals not passing the front of the head, a rayloss 

 space between the cephalic portion and the body of the fin ; lateral 



edge of the fin incurved at the head, and spreading outwards at the Classifica- 

 third gill-opening. Three species. ^Joq 



In our preceding compendious review of the class of *^°' 

 fishes, we have, as already stated, taken as our almost ex- 

 clusive authority, with regard to structure, Professor Rich- 

 ard Osven, late Curator of the Museum of the College of 

 Surgeons of London, and now Zoological Superintendent 

 of the British Museum. From his lectures delivered in 

 1844 and 1 846 before the college our fiicts have been taken. 

 The great Histoire des Poissons of Cuvier and Valen- 

 ciennes, which closed with the 22d volume in 1849, has 

 been our text-book for the characters of families and genera 

 of most of the osseous fishes, as well as /or the few remarks 

 we have made on their species. Several families and groups 

 of families not included in that work have been charac- 

 terized by the labours of Dr Kau|) of Darmstadt ; and for 

 our analysis of the Plagiostomi, we have taken for our sole 

 text-book the treatise of Miillerand Henle on that subject, 

 published in 1838. Some other vvorks of Johannes Miiller 

 that we wished nmch to consult, were not to be found in 

 those public libraries to which we had access, and we have 

 been unable therefore to give the latest views of that very 

 distinguished physiologist. We could not within encyclo- 

 pcedic limits enter into the discussion of disputed points, or 

 entertain questions respecting priority of names, and we 

 therefore have with scarcely an exception adopted the gene- 

 ric names of the authorities we have mentioned, and also 

 their family groups, occasionally, however, for the sake of uni- 

 formity changing the few terminations of the names of the 

 latter into idee where that had not been previously done, 

 intending by such uniformity of termination to denote more 

 readily the rank of the group in the system. The labour of 

 clearing up the intricate synonyms that have crept into the 

 science, is one of the greatest, and is certainly the most irk- 

 some, that the ichthyologist has to encounter, and one whose 

 successful results are generally shown by the adoption of a 

 single word, giving no indication to the uninitiated of the 

 time, and research, and thought they have cost. It is, how- 

 ever, a labour that cannot be lightly passed by ; for without 

 a correct determination of the species the descriptions are 

 useless or encumbering to science. Without such careful 

 j)reliminary work no one can enter at all upon the subject of 

 the geographical distribution of species. Yet that branch 

 of ichthyology, no less than the habits of the species, is of 

 vast importcince to a maritime nation, desirous of extending 

 her fisheries, and thereby increasing the supply of a most 

 healthy and nourishing food for her teeming population, 

 and raising new nurseries tor seamen. 



However desirous we may be of adding a few words on 

 the geographical distribution of fish, the time has not yet 

 arrived tor enunciating many observed fiicts. There is as 

 yet no general list of species comprising the whole class, 

 and in local lists our conclusions are universally marred by 

 the clashing of synonyms, and the superabundance of nomi- 

 nal species. A work, however, has been going on for some 

 years, silently almost, and without attracting a tithe of the 

 notice it deserves from scientific zoologists, but which, 

 when completed, will supply exacriy what is required. We 

 mean the Zoological Catalogues of the British Museum, 

 now in the course of publication in parts. The enlightened 

 plan of this catalogue, as conceived by Dr John Gray, the 

 keeper of the zoological department of the Museum, is to 

 comprehend descriptions of all known species, of which 

 specimens are to be found in any of the great European 

 museums, with a comparison of the actual specimens in 

 every instance in which that can be effected. In this way, 

 not only are the species in the British Museum correctly 

 named and pointed out, so as to relieve future inquirers of 

 a lo.ad of labour ; but the species not to be found in the 

 Museum are also indicated. We know of no work on Na- 

 tural History better planned, nor one that is likely to have 



