ICHTHYOLOGY. 



325 



Genus n. Spinax, Bonap. Head arched. Snout blunt; nos- 

 trils at the extremity of the snout. Folds at the corner of the 

 mouth very large, naked; under one encircling the under lip and 

 J uniting with its fellow ; a lahial cartilage at the upper corner of 

 the mouth. Under teeth as in Acanthius, but without keel and 

 basal apophysis ; upper teeth as in Seiillium, but with a longer, 

 straight, conical, mesial cusp, and two pointed lateral toothlets on 

 each side. No tail-pits. Claspers not furnished with a prickle. 

 Curved hairs in place of scales. One species. 



Genus 111. Centrina, Cuv. Snout short, thick, and flat, with 

 the nostrils near its edge; nasal flap quadrilateral. Fold at the 

 corner of the mouth naked, blending on the mesial line with the rest 

 of the integument. .Spout-holes very large, behind and somewhat 

 above the eyes, vertical, and crescentic, with a single flap. Upper 

 teeth slender, conical, straight, and feebly incisorial, connected 

 with the integument of the front of the jaw, and notched in the 

 middle of their base ; under teeth very nearly straight, broader 

 and flatter than the upper ones, keenly cutting, sub-equilateral 

 and finely serrated, with their bases nearly quadrangular; mesial 

 tooth single, perfectly equilateral. Dorsal spines enveloped in 

 skin to their points ; no under caudal lobe and no notch. Male 

 claspers soft, spineless. Scales consisting of an upright cusp on a 

 quadrangular base. One species. 



GISNDS IV. Centeophords, MiilLand Henle. Head flat. Nos- 

 trils near the end of the snout. Folds at the corner of the mouth 

 naked, large, and deep, with a slit running backwards from them. 

 Spout-holes behind and above the eyes, furnished with a flap. 

 Fourth and fifth gill-openings near each other. Teeth of the under 

 jaw as in Acanthias, and either serrated or entire ; their roots a 

 middle upright keel with a tranverse exterior lobe ; upper teeth 

 straight, equilateral with quadrangular bases traversed by two 

 crossing keels, no denticulatinns, no accessary prongs or toothlets ; 

 no mesial tooth. No tail-pits. Male claspers with an exterior 

 prickle near their tips. Two species. 



Genus V. Oenteoscyllium, Mull, and llenle. Upper and under 

 teeth similar, straight, pointed with one or two lateral cusps or 

 toothlets, as in ScylUum. Distinguished from Spinax by the teeth 

 being alike in both jaws. Scales pointed, with a stellate base. One 

 species. 



Family X.— SCYMNID.E, Miill. and Ilenle. 



Sci/mni, Mull, and Henle. Dorsal fins without spines. Upper 

 teeth pointed ; lower ones trenchant, not denticulated. No tail-pits. 



Genus I. Scymnus, Cuv. Head either flat, or compressed on 

 the sides. Spout-holes far behind the eyes. Teeth of the upper jaw 

 upright, curved ; under teeth broader, with an upright or an in- 

 clined edge. Gill-openings small. No tail-pits. 



Sab-Genus I. Sctimniin, with lancet-shaped under teeth, convex 

 anteriorly, sharp on the sides, rising from a high base ; the me- 

 sial tooth below as large as the others, and a biiobed root longer 

 than the cusp ; upper teeth standing straight forwards, with their 

 sides inclined outwards. Claspers without a prickle. Two species. 



Sub-Genus II. Lmmaryus, Mull, and Ilenle. Upper teeth small, 

 longer than wide, conical, feebly incisorial, without serratures ; an 

 upright anterior keel, and a notched base ; under teeth broader 

 and longer, with a recumbent edge as mAcanihias, no serratures; 

 and a long flat root, concave lengthways, and keeled perpendicu- 

 larly anteriorly. Male claspers with a prickle. Three species. 



Genus II. KcHiNORHiNUS, Blain. ffoniodiw, Agass. Head flat; 

 corner-pits of the mouth widely apart. Teeth broad and low, with 

 a nearly horizontal edge ; on the lateral edge, from one to three 

 small cusps or toothlets ; a space at the symphysis of the under 

 jaw, with a very small mesial tooth in its centre. First dorsal over 

 the ventrals ; no under caudal lobe. Gill-openings not wide, all 

 before the pectorals. One species. 



Genus HI. PKrsTioPHORus, Jliill. and Ilenle. Separated from 

 Pristis by the want of a naso-pectoral cartilage, the posterior wall 

 of the nose being in this genus formed by the skull itself. Snout 

 greatly elongated, beset on both sides with spines, attached to the 

 skin only. A long barbel from the under surface of the snout. 

 Mouth transverse. Teefh pavement-like, with a short mesial cusp, 

 as in the male rays. First dorsal over the space between the pec- 

 torals and ventrals. .Side of the snout keeled. Fourth and fifth 

 gill-openings approximating. Two species. 



Family XI.— SQUATINID/E. 



Sqxtatin(B, MQll. and Henle. Body flat above and below. Mouth 

 at the extremity of the snout. Eyes on the dorsal aspect. Spout- 

 holes large, behind the eyes. Pectorals large, their expanded roots 

 interposing between the head and body, but divided from them by 

 a furrow, in which are situated the closely approximated gill- 

 openings. 



Gen-US I. Squatina, Dum. Both dorsals on the tail, which is Classifica- 



keeled on the sides. Male claspers small and weak. Scales coni- tion 



cal, with a terminal point. Teeth conical, irregular, with inter- Sharks, 

 spaces. Two species. 



(G.) Sharks, similar to those of division B, in having a nic- 

 titating membrane and no spout-holes, and in the po- 

 sition of the spineless dorsals ; hut with a lateral exten- 

 sion of the skull at the orbits, which is greatest in the 

 adults. 



Family XII.— ZYG.'ENID.E. 



Sharks, head flat, with the orbits largely extended latterly, and 

 the snout truncated, or hammer-headed ; a form of head not found 

 in any other group of fishes. 



Genus I. Zyg.en.e, Cuv. (Sphyrna, Rafin.) Sphyrnia, and 

 Sphyrna, Rafin. Front of the head transverse to the ends of the 

 lateral orbital extensions of the skull. Nostrils on the front 

 border ; nasal flap small, triangular on the inner edge of the nos- 

 tril. Labial cartilages small. Teeth alike above and below, beinw 

 a compressed pyramid, with an entire or serrated exterior basal 

 ledge ; a mesial tooth in both jaws. First dorsal near the pectorals- 

 second one over the anal. Distinct tail-pits. Oviduct villous ' 

 yelk-bag connected to the sides of the ovisac. Four species. ' 



Fig. 136. 

 Head of Raia Lemprieri. 



RAYS. 



This sub-order, femiliarly known by the name of Skates, 

 has for the general character of its form the extreme depres- 



Fig. 137. 

 Vrolophus ephippiatua, Australia. 



sioii ot its body, and the lateral expansion of the pectoral 



