ICHTHYOLOGY. 



231 



Classifica- It is a well-known law in chemistry, that when two fluids diverge posteriorly. Like Amphipnous and Ophisternon, the ex- Classifica- 

 tion— Ma- of different densities come in contact, the temperature of «"<>■■ gill-opening is angular, and below the outer integument there tion—Ma- 

 lacopteri. thg mixture is elevated for a time, in proportion to the l^^" 'J'<""'"-a°ous partition between the gills. One species, M. lacopteri. 



^""^/'~~^ difference in density of the two fluids, from the mutual ' ^^»^,«-^ 



jienetration and condensation. Such a mixture is constantly 

 taking place in rivers that run into the sea, and the tempe- 

 rature of the mixed water is accordingly elevated." As Eels 

 are well known to breed in ponds, it may be inferred that 

 their descent to the brackish water, though customary, is 

 not indispensable. They sometimes attain a great size. 

 The species (or variety) called the Sliarp-nosed Silver Eel 

 has been taken near Cambridge of the weight of twenty- 

 seven pounds. 



Order II.— MALACOPTERI. 



Pkysostomi, Miill. Endo-skeleton ossified ; exo-skeleton, in most 

 as Cycloid, in a few as Ganoid scales. Fins supported by rays, all, 

 save the first, sometimes in the dorsal or pectoral, soft or jointed 

 abdominal or apodal. Gills free, operculate ; a swira-bladder and 

 air-duct. 



Sub-Order I.— APODES ANGUIFORMES. 



Malacoptert/gii apodes (partim), Cuv. Elongated fish more or 

 less approaching to vermiform, covered with a thick slimy skin ; 

 the majority scaleless, but in some genera small scales are imbedded 

 in the skin. No developed ribs in the skeleton. Stomach caecal. 

 Pancreatic c«cal appendage to the intestine wanting. The greater 

 number have a swimming-bladder, which is often very curiously 

 formed, but never double. Fin rays simple, not jointed. 



Section A. — Phaneromycteres. 



Labial olfactory organ opening by the posterior nostril on some 

 part of the head above the mouth, so as to be exposed. 



Family I.— SYNBRANCHID.^, Kaup. 



Uni-aperturidce, auct. Both gill-openings enveloped by a border 

 of the common integument, so as to present externally only a single 

 medial orifice. Pectorals and other fins wanting, or almost obso- 

 lete. Species few, confined to the seas of Asia and South America. 



Genus I. Amphipnous, Mull. {Umbranchapertura, Hamilt. 

 Buch.; Synbranchus, Cuv. ; Ophichthys et Pneumabranchus, M'Clell.) 

 A membranaceous partition separates the branchial cfi'erent 

 tubes, and is continued to the verge of the common orifice. Four 

 gills, the third one having short fringes ; the fourth, a membrane 

 ■with merely faint notches on its extremity. Vomerine teeth strong, 

 in two rows, eight in each, standing well apart; palatine teeth 

 small and thin, a little larger on the point of the bone ; mandibular 

 teeth pluriserial at the sympliysis, uniserial towards the corner of 

 the mouth. On the occiput there is a sac which can be filled with 

 air, and is connected with the gills. Fine scales form a multitude 

 of elevated longitudinal lines on the body. The only trace of a 

 fin is a slight one on the thin tapering end of the tail. One species, 

 A, cuckia. 



Genus 11. Ophisternon. (Unibrancliapertura, Lacep.; Ophi- 

 sternon, M'Clell. ; Synbranchus, Cant, and Bleek.) Four fringed 

 branchial arches, which discharge the water that has passed over 

 them by two tubes divided by a thin partition, inclosed by the 

 skin of the throat so as to form one transverse oval opening. No 

 air-bag on the occiput, and no swim-bladder. Branchiostegals six, 

 bony. Posterior apertures of the nostrils between the eyes ; an- 

 terior nostrils minute, one on each side of the snout. Teeth fine, 

 blunt on the upper jaw, almost setaceous, crowded into a triangle 

 on each side of the symphysis; vomerine teeth larger, in a single 

 series ; mandibular ones somewhat bigger still, and truncated. One 

 species, 0. bengaletuis. 



Genus III. Synbranchus, Bloch. Have all the characters of 

 Ophisternon, but the four fringed gills are not separated under the 

 throat by a partition, and the solitary gill-opening does not make 

 the angular inflection that it does in Monopterus, Ophisternon, and 

 Amphipnous. Hinder nostrils opening above the eyes, and capable 

 of being shut by a cutaneous flap. Two species, one Indian, the 

 other South American. 



Genus IV. Monopterus, Lacep. Three gills only. No occi- 

 pital air-bags. No protruding nasal teeth; the palatine teeth meet 

 in an angle with the vomerine ones anteriorly, and are there pluri- 

 serial, but diminish to two and one row towards the corner of the 

 mouth ; vomerine teeth triserial anteriorly, uniserial posteriorly ; 

 ranged in two bands, which meet m an acute angle anteriorly, and 



Family II.— MURvENID^, Kaup. 

 In most of the genera no pectorals. Gill-openings lateral. Skin 

 smooth and slippery, without scales. Mostly or wholly marine fishes. 



(a.) SUB-FAMILY. — MURJENIN^. 



Uniserial teeth on nearly all the dentiferous bones of the mouth. 



Genus I. Mur^na, Kaup. Uniserial nasal teeth, three on the 

 mesial line. Twenty-four species. Figure 64 represents Murcena 

 pavonina. 



Genus II. Sidera, Kaup. Only one short conical tooth on the 

 mesial line ; biserial, low, granular teeth on the vomer, the rows 

 coalescing in a point posteriorly; opening of the jaws not wide. 

 Skin spotted. Two species. Figure 65 represents Sidera pan- 

 tkerina. 



(b.) sub-family.— THYRSODEIN.E. 



Within the outer palatine teeth, a second row that varies much 

 in the number of teeth which compose it. 



Genus III. Enchelynassa, Kaup. Fore nostrils short, infun- 

 dibuliform, and capable of being closed by a cutaneous tag of its 

 hinder border ; hinder nostril longish, oval, surrounded by an ele- 

 vated cutaneous border, and nearly as large as the eye. Rictus of 

 the jaws gaping in the middle, owing to the length of the teeth ; 

 nasal teeth, five long ones anteriorly, followed by three or four 

 smaller ones ; in the second row three long moveable teeth standing 

 near the corner of the eye ; nineteen greater and smaller palatine 

 teeth, with six more acicular ones in an interior row; on the mesial 

 line of the nasal, three long moveable teeth ; on the vomer, two 

 short conical ones; mandibular teeth, twenty-two small ones in the 

 exterior row, and five long ones in an interior row. One species. 

 The teeth are shown by figure 58. 



Genus IV. Eurymictera, Kaup. Fore-nostril tube projecting 

 outwards beyond the lip ; lips expanding on the upper and under 

 jaws ; hinder nostril over the eye, and encompassed by an infundi- 

 buliform border. Nasal teeth eleven, with five small intercalary 

 ones in the posterior part of the row; palatines thirty in the outer 

 row, five larger ones forming an inner row ; from seven to ten on 

 the vomer, the extreme ones minute; mandibulars twenty-seven of 

 a side, with five bigger ones near the symphysis in a second row. 

 Body slim. Jaws deeply cleft. Dorsal fin commencing at the oc- 

 ciput. One species. 



Genus V. Enchelycore, Kaup. Jaws incapable of shutting 

 close from the length of the teeth; hinder nostril strikingly large, 

 longer than broad, and situated before the eye; fore nostril-tube so 

 unusually short that it does not pass over the edge of the lip, and 

 it has no lid ; eye in the middle of the length of the snout ; the thin 

 outstretched upper jaw curves upwards. Twenty-four slender teeth, 

 some of them elongated, forming the outer row on the nasal bone; 

 eight moveable latter ones in a second row ; three on the mesial 

 line; eighteen outer palatines; three moveable bigger ones making 

 an inner row; about fifteen small, pointed vonierines, and thirty- 

 seven fine mandibular ones, with two bigger moveable ones at the 

 symphysis. One species. 



Genus VI. Thyrsoidea, Kaup. Murcence in the construction 

 of the fore and hinder nostrils, and presenting no prominent cha- 

 racter whereby they may be distinguished from the Murmnw proper, 

 except that they possess a more or less complete second or inner 

 row of pointed palatine teeth. 



The numerous species (33) may be grouped according to the 

 number of rows of their vomerine and palatine, and by the patterns 

 which the colours of their bodies assume ; — some are reticulated, 

 others spotted, others again of one uniform colour in the upper, or 

 both above and below. 



Genus VII. Limamur.ena, Kaup. Abbreviated Thyrsodeince, 

 whose hind nostril-tubes project still more than those of Muraena 

 helena. Ten or twelve nasal teeth, with some scarcely perceptible 

 ones at their bases : three on the mesial line ; jjalatine teeth biserial, 

 but the inner row of six generally defective, sometimes altogether 

 wanting ; four to six vomerine teeth ; mandibulars uniserial, nine 

 of them taller than the fourteen others. 



Head elongated ; snout pointed ; front nostril-tubes projecting 

 over the edge of the lip ; hinder ones a little exceeding the dia- 

 meter of the eye in length. Dorsal fin commencing at the occiput. 

 One species. 



Genus VIII. Polyukanodon, Kaup. Thyrsodeince, with three 

 rows of acute teeth on the palatine bones ; fourteen uniserial nasal 

 teeth ; five or six uniserial vomerine teeth, mandibulars quadri- 

 serial anteriorly, biserial towards the corner of the mouth. One 

 species. 



