324 



ICHTHYOLOGY. 



Classifica- holes small, elongated op round. Teeth alike in both jaws, com- 

 tion — ■ pressed, with cutting edges, and a cusp pointing obliquely out- 

 Sharks, wards ; edges smooth, or serrated on the outside or on both sides. 

 '< ^ -^ J Upper caudal lobe with one or two notches near its end. Tail-pits 

 absent or present. Intestinal valve spiral, or rolled lengthways. 

 Scales small, three-keeled, with a medial cusp. 



Gends I. Galeus, Cuv. ^pout-holes longish, half the length 

 of the orbits behind the eyes; pupil round above, angular below. 

 Teeth smooth on the inner edge, serrated on the outer one ; cusp 

 smooth, upright; mesial teeth straight, jagged at the base on both 

 sides, and as large as the others. No tail-pits. A notch on the 

 upper caudal lobe. Intestinal valve spiral. Two species. 



Genus II. Galeocerdo, Miill. and Henle. Spout-holes very 

 small, half the length of the orbits behind the eyes ; pupils as in 

 Galeus. Corner-pits of the mouth and labial cartilages indistinct. 

 Teeth denticulated on both edges; outer edge prolonged in form 

 of a coarsely jagged base ; a single mesial tooth on both jaws, with 

 the point turned to a side. Upper caudal lobe long and pointed ; 

 two notches on the under caudal border, one of them at the end of 

 the spine. A tail-pit above and below. Gut-valve rolled length- 

 ways. Two species. 



Gknvs III. LoxoDON, Bliill. and Henle. Pupil round. Teeth 

 alike in both jaws, oblique-edged, not serrated, basal projection on 

 the outside also entire ; a mesial tooth in the upper jaw, none in 

 the lower one. Spout-holes small, close behind the eyes. Tail-pits 

 above and below. A single notch in the upper caudal lobe. One 

 species. 



Genus IV. Thalassorhinus, Valenc. Pupil perpendicularly 

 oval. Nasal flap very short. Teeth triangular, without a serrated 

 basal ledge. Spout-holes pretty large. Tail-fin as in Carcharias, 

 with a single notch ; tail-pits above and below conspicuous. Intes- 

 tinal valve rolled lengthways. Two species. 



Genus V. Triakis, Mull, and Henle. Head flat, blunt. Nasal 

 flap broad, moderately long ; large pits at the corners of the mouth. 

 Labial cartilages. Spout-holes of medium size. Teeth and tins as in 

 Scyllia. Under caudal lobe indistinct. Tail-pits wanting. Scales 

 three-keeled and three-pronged. One species. 



Genus VI. AIustelus, Artedi. Large spout-holes. Long orbits. 

 Nictitating membrane puffed out from the under eyelid. Teeth 

 pavement-like, flat, without cusp or cutting edge, resembling those 

 of the Rays. Labial cartilages at the corners of the mouth, and also 

 deep pits. Nostril bordered above by a three-sided cutaneous lobe 

 with a rounded tip and a short blunt lobule on the outside. First 

 dorsal nearly in the middle between the pectorals and ventrals ; 

 caudal short. Tail-pits indistinct. Intestinal valve spiral. One 

 species. 



(D.) Sharks, inth two dorsals and an anal ; the first dor- 

 sal over the space between the pectorals and ventrals. 

 Spout-holes, hut no nictitating memhrane. 



Family IV.-LAMNID^. 



Lamn^, Miill. and Henle. Gill-openings large, all anterior to 

 the pectorals. Second dorsal and anal roundish, of equal size, and 

 opposite to one another. Tail-pits evident. Caudal crescentic. 

 Tail keeled on the sides. Spout-holes very small. Intestinal valve 

 spiral. 



Genus I. Lamna, Cuv. Snout a pointed three-sided pyramid; 

 nasal flap short, three-sided. Spout-holes very small, far behind 

 the eyes. Teeth compressed, not serrated, triangular, with an acute 

 basal toothlet on each side of the older ones ; surface of the base that 

 rests on the jaw deeply concave ; in place of mesial teeth, a vacant 

 space above and below. Skin smooth. Scales very small. One 

 species. 



Genus II. Oxyrhina, Agass. Snout, spout-holes, and fins of 

 Lamna. Teeth very thick, narrow and long, nail-shaped, curved, 

 without basal toothlets ; each tooth flat before, convex behind, di- 

 minishing rapidly in size towards the corner of the mouth, and 

 double rooted with a deep notch between the roots; a vacant me- 

 dial space on both jaws, and the third tooth of the upper jaw smaller 

 than its neighbours. Three species. 



Genu^ III. Carcharodon, Miill. and Henle. Snout, position 

 of fins and spout-holes, as in Ojujrhina. Teeth of Carcharias, but 

 straight, equilateral, and without a basal ledge ; no mesial tooth ; 

 the third upper tooth is a little smaller than the adjoining ones. 

 One species. 



Genus IV. Selache.Cuv. Snout short, blunt ; spiracles small. 

 Gill-openings very large, nearly meeting on the throat. Teeth very 

 small and numerous, conical, without toothlets or lateral notches, 

 curved backwards. Scales small, with radiating curved points, so 

 that the skin feels rough to the finger drawn over it in any direc- 

 tion. One species. S. maxima. 



Sharks. 



Genus V. Odontaspis, Agass. (Triglochis, Miill. and Henle.) Classifica- 



Gill-openings large, wholly before the pectorals. Spout-holes very ^q^ 



small. Transverse folds on the throat; a stout triangular flap above 

 the nostril; no upper corner fold to the mouth. Second dorsal v 

 and anal large ; upper caudal lobe elongated as in Carcharias. 

 Tail-pits indistinct or wanting. Fore teeth very long, conical, sim- 

 ple, or with one or more very sharp basal toothlets; towards the 

 corners of the mouth the upper teeth are more incisorial and dimi- 

 nish rapidly in size ; the under teeth are similar in form ; roots of 

 the tooth divided into two branches by a middle hollow. Second 

 dorsal over the space between the ventrals and anal. Scales three- 

 keeled, the keels ending in sharp points. Two species. 



Family V.— ALOPECIID^, Miill. and Henle. 



Snout short and conical; spout-holes very small; nostrils small 

 with a short superior flap; no labial cartilages. Gill-openings 

 small as in Carcharias ,• the last one over the pectoral. Teeth com- 

 pressed, not serrated on their cutting edges, alike in both jaws ; no 

 tooth on the mesial line; a smooth crescentic fold of skin behind 

 the upper teeth. Second dorsal opposite to the anal, very small ; 

 pectorals falcate; upper caudal lobe very long, with a pit at its 

 root. Scales small, three-pronged. Intestinal valve spiral. 



Genus I. Alopecias, Miill. and Henle. (Alopias, Kafin.) Teeth 

 having the outline of a sharp isosceles triangle in both jaws. Upper 

 lobe of the tail as long as the body. One species, A. vulpes. 



Family VI.— CESTRACIONTID^. 



Cestraciontes, Miill. and Henle. Mouth at the fore end of 



the snout. Nostrils slit to within the mouth. Spout-holes distinctly 

 visible, rather behind the eye. Gill-openings small, the last one 

 above the pectorals ; a spine forming the front of each dorsal. 

 Tail short; its upper lobe notched underneath. Pavement-like 

 teeth in rounded oblique scrolls, like the spines of some univalves. 

 Genus I. Cestracion, Cuv. Caudal wide, and strongly notched 

 below. Two species, Pacific Oceau, from Japan to Australia. 



Family VII.— RHINODONTID^, Mull, and Henle. 



Rhinodontes, Miill. and Henle. Head flat. Mouth and nos- 

 trils at its extremity ; nasal flap triangular. Teeth extremely small, 

 and very numerous, card-like, conical. Spout-holes very small. 

 Gill-openings diminishing in size as they recede from the head ; 

 the last one above the pectoral. Caudal crescentic, its upper lobe 

 not notched. Lateral keels on the keel and pits. Intestinal valve 

 spiral. 



Genus I. Rhinodon, Smith. One species. 



(E.) Sharks, with one anal and only one dorsal. 



Family VIII.— NOTIDANID^, MuU. and Henle. 



Gaki, without a first dorsal. Upper corner-fold of the mouth 

 very large, under one small; no nictitating membrane. Spout- 

 holes vertical, small. Six or seven gill-openings decreasing gradu- 

 ally in size, all before the pectorals. A mesial upper tooth ; to- 

 wards the corners of the mouth the teeth are low and fiat ; the others 

 are triangular above, serrated below, the foremost ones crowded 

 and curved. A small inferior caudal lobe, obliquely truncated and 

 notched at the end. No tail-pits. Intestinal valve spiral. 



Genus I. IIexanchus, Rafin. Six gill-openings. One species. 



Genus II. Heptanchus, Rafin. Seven gill-openings. Two 

 species. 



(F.) Sharks, with spout-holes. Two dorsals ; no anal ; no 

 nictitating membrane. Five gill-openings, all before 

 the pectorals. Intestinal valve spiral. 



Family IX.— SPINACID^, Miill. and Henle. 



Each dorsal fronted by a spine. 



Genus I. Acanthias, Bonap. Head flat. Large pits at the 

 corner of the mouth. Two labial cartilages. Mouth very flatly 

 arched. Spout-holes large, behind and rather above the eyes, with 

 a thick border springing from their fore edges ; orbits long. Teeth 

 on both jaws incisorial, the edge almost horizontal, with the point 

 directed laterally, and the base keeled interiorly. First dorsal 

 over the space between the pectorals and ventrals ; second dorsal 

 between the ventrals and caudal ; upper caudal lobe the bigger 

 one. An upper tail-pit in some. Male claspers tipped by a move- 

 able spine. Scales heart-sbaped, with a middle cusp and one or 

 more keels. Four species. 



