lf.8 



I'r.OTOr TEEES.- 



-FISHES.- 



■ Pkotoptekes. 



Family VII.— MYLIOBATIDS {MyUohatklic). 



Ill this family the pectorals are interrupted on the 

 Bides of the head, which is more prominent than oilier 

 memhers of the Raian order ; but at the proximal 

 extremity of the disc the pectoral rays are developed 

 anew, constituting a kind of cephalic fin. The nasal 

 lappets of each side coalesce mesiad into a quadrilateral 

 fringed flap, which reaches to the mouth. Nostrils 

 approximating to tlie mesial plane, where they are 

 separated by a thin bridle, which has a lateral con- 

 nection with each corner of the transverse mouth. 

 Teeth broad and flat in geometrical polygonal figures, 

 funning plates which extend far back into the mouth, 

 and arc bounded posteriorly in both jaws by mem- 

 branous folds. Eyes separated from the spout-holes 

 by broad bridges of integument, and situated on the 

 sides of the skull. Tail long and whip-like, with a 

 dorsal fin at its root and a spine behind it. 



The genera are — Mi/Uoballs ; u^tohaiis ; and Rkluoplcra. 



The I'aglc-ray {Mijllubatls arjidla) frequents the 

 IJiitish seas. 



Family VIIL— CEPHALOPTEPJDS 

 {CephaloiHcridce). 



In this family the proximal end of the head is straight 

 transversely, but with an ear-like appendix on each 

 side, curving towards the ventral aspect, and formed 

 by a prccephalic detachment of the pectoral fin. 

 Mouth in front or beneath, reaching nearly from one 

 of these ear-like fins to the other. Nostrils widely 

 apart. Eyes lateral, situated immediately before the 

 beginning of the proper pectorals, which have a 

 great lateral expansion. Spout-holes on the dorsal 

 aspect and rather distant from the eyes. Tail as 

 long as the body or longer, with a spine behind the 

 dorsal fin. 



The genera are — Ccphuluptcra aud CeraJopfcra. 



The Horned-Eay {Cephaloptera Giorna) has been 

 captured on the coast of Ireland. Ceraloj/ti'nr; of great 

 size, exceeding twenty feet in length, have been taken 

 in the West Indies ; and traditions of some that were 

 seen having a still vaster spread of the pectorals are 

 current in Carbadocs. 



Order XIIL— PROTOPTERES {Protoplcn). 



Tins order was named by Professor Owen from the 

 embryonic condition of the vertical fins, which, like 

 tliose of the tadpole of a frog, are developed on the 

 upper and under edges of the animal from a continuous 

 fold of the integument, and, as in the order of Dermop- 

 teres, are persistent in the Protoptcres and Lepidosirens. 

 Miiller in allusion to tlie resemblance of these fishes to 

 another tribe of Batraohians, named the order Sire- 

 noids. The characters that have been assigned to this 

 group, are the internal skeleton in part ossified, in part 

 cartilaginous ; vertebral column retaining the embry- 

 onic form of a " notochord," and the dermal skeleton 

 existing in form of cycloid scales ; the pectorals and 

 ventrals, which are situated on the abdomen, each in 

 form of a single tapering, flexible filament or barbel, 

 supported internally by a soft cartilaginous ray. The 

 gills are filamentary and free ; there is no pancreas ; 

 tlie swim-bladder appears as a cellular lung with an air- 

 duct ; and there is a spiral valve in the intestines. The 

 Protopkrus anncctcns of the Gambia, and the Lepiido- 

 sircns jiaradoxa of the Amazon, are the representa- 

 tives of the order. 



The Gambia Protoptcre inhabits districts which are 

 flooded by tropical rains, and leads an active piscine life 

 as long as the waters prevail ; but when the flood is 

 passing off, this curious animal burrows into the mud, 

 which a vertical sun soon bakes into a hard crust. An 

 aperture, however, is left in this clayey cell by which 

 some air is admitted, and therein the fish, besmeared by 

 a thick layer of mucus passes, the dry season, rolled up 

 in a torpid condition. Protopteres have been brought 



to this country imbedded in the clay, and when placed 

 in a stove and well watered, have come forth in a vigor- 

 ous condition. The air-bladder is supposed to perform 

 the function of a lung during the time that the Protoptcre 

 is secluded from the water; and tlie communication of 

 the air-tube with the oesophagus is fortified by a tracheal 

 cartilage. The disposition of the gills is peculiar. In 

 front there is a uniserial or half gill, but the first bran- 

 chial arch is united to the second, and is not furnished 

 with gills ; the gills of the second arch are biserial, 

 long, and thread-like ; the third arch is merely fringed 

 or denticulated on the edge ; the fourth arch is united 

 by membrane to the third, and has no gills ; but tho 

 fifth, or pharyngeal arch, supports a uniserial gill. 

 There are only three passages between the gills, and 

 only a portion of the blood is oxygenated, the blood in 

 the arteries that supply the gill-less arches joining the 

 circulation without undergoing that process.' 



Naturalists are divided in opinion as to those animals 

 being fishes or reptiles. Professor Owen's reasons for 

 ranking them in tho first of these classes are — the gela- 

 tinous condition of its notochord, the form of the trans- 

 verse processes of that column, the attachment of the 

 scapulo-coracoid arch to the skull, the branohiostegous 

 membrane and the operculum covering the permanent 

 gills, the absence of a pancreas, the presence of a spiral 

 intestinal valve, the position of the vent, the muciferous 

 pores on the head and lateral line, and the nasal sacs 

 shut off from the interior of the mouth. 



Tho Protoptcre is much like an Opbidium with an 

 acute tadpole-like tail. 



END OF FISHES. 



