232 



Chondrop- 

 terygii. 

 Selachii. 



ICHTHYOLOGY. 



■ the presence or absence of apertures behind the eyes, and 

 of an anal fin. 



Without Air- Holes, with Anal Fin. 



Cabcharias, Cuv. This well-known and numerous 

 group have extremely sharp-pointed teeth, often serrated 

 on their edges. Of these, their jaws are armed with se- 

 veral rows, which they have the power of elevating or de- 

 pressing, and can use with remarkable effect, from the 

 strength of the muscles moving the lower jaw. The first 

 dorsal fin is considerably before the ventrals, and the se- 

 cond is almost opposite to the anal. The posterior bran- 

 chial apertures are over the pectoral fins. 



The best-known species is Sg. carrharias, or white shark, 

 the dread of seamen in hot climates, and not unfrequent- 

 ]y seen on our own coasts. It is a very large fish, grow- 

 ing, it is said, to more than thirty feet, and often observed 

 to measure from fifteen to twenty-five feet. The teeth 

 are, in full-grown animals, in six rows ; those in the up- 

 per jaw are nearly isosceles triangles, with sharp, dentated 

 edges ; those in the lower jaw have a narrow lancet- 

 shaped point on a broader basis, with smooth-cutting 

 edges. From the position of the mouth in this species, 

 the animal turns on its side on seizing its prey. Its vo- 

 racity is well known, and it has been seen to leap out of 

 the water in its eagerness to snatch a suspended morsel. 

 The jaws are so powerful as to bite at once through the 

 body of a man. The gullet is very large, and the intes- 

 tine short. One killed near Marseilles is alleged to have 

 had the entire body of a man, and several fisli, in its sto- 

 mach ; and one captured oft' the island of St Margaretta 

 is even said to have contained the whole body of a horse. 

 This one had the enormous weight of 1500 pounds. 



The sailors believe that the pilot-fish, which is so con- 

 stant an attendant on this species, directs him to his 

 prey ; and, by touching his head, warns him against a 

 baited hook. Certain it is, that the pilot-fish have been 

 repeatedly seen clinging to a shark wl ile he was hoisting 

 on deck, and appeared as if distressed on separation from 

 their formidable comrade, who has never been known, in 

 his utmost voracity, to attack his friendly guides. What 

 the instinct is that produces this attachment is unknown ; 

 but probably it depends on the pilot (Naucmtes ductor) 

 obtaining its subsistence from the remains of the shark's 

 prey, as the jackal does from that of the lion.' 



Little of the age or development of this species is as- 

 certained. The female has been known to contain many 

 ova ; but only three or four are perfected at a time, and 

 impregnation may take place long before the fidl growth 

 of the animal. A shark ten feet long has been found to 

 contain forty ova, three or four of which were near ma- 

 turity. 



Sq. vulpes, the thrasher, so called from the inordinate 

 length of his tail, which is almost half the length of the 



Selachii. 



animal. It is the upper lobe-which is thus elongated ;Chondrop- 

 and as it has the fin along its under side, it gives the or- }erygii. 

 gan some resemblance to a fox's tail. It grows, even in 

 our own seas, to a large size. Pennant measured one thir- 

 teen feet, of which the tail was more than six feet. The 

 body is round, the nose short but pointed ; the teeth are 

 small, but sharp. 



It is this species which is said to attack various Cetacea, 

 which it harasses by dealing them violent strokes with its 

 tail, when they rise to the surface for the purpose of 

 breathing. 



Sq. glaucus, the blue shark, is a very bold and vora- 

 cious fish, not unfrequent on our .coasts during the her- 

 ring season. It grows to ten, or even fourteen feet in 

 length ; is of a slaty blue above, and smoother than the 

 rest of the genus. Head large, muzzle very pointed ; 

 mouth large ; teeth almost triangular, long, sharply point- 

 ed ; the upper curvilinear, bent outwards ; the lower 

 straighter, and all dentated. 



The nostrils are long and transverse. Artedi and others 

 have noticed a triangular fossule, with its apex downward, 

 on the lower part of the back. 



To this subdivision we must refer the following species: 



Sq. ustus, Dum. ; S. ocellatus ; Sg. ciliaxis ; and several 

 Indian species, described by Russel. 



Lamna, Cuv. This subdivision is distinguished from 

 the last by having all the spiracles hefore the pectoral 

 fins, and by having a projecting pyramidal snout. 



Sqtuilus corniibicus, portbeagle shark, is well known in 

 the Mediterranean and British seas, and is formidable on 

 account of its teeth and size. One caught in Ib34, on 

 the coast of Caithness, now in the College Museum of 

 Edinburgh, measures eight and a half feet, and is in girth 

 four feet eight inches. Its teeth are upwards of an inch 

 in length, extremely sharp, but not serrated. There are 

 three rows of teeth, of an elongated form, slightly bent 

 outward, and extremely sharp. The nostrils are under 

 the snout, two and a half inches from the eye.^ The cir- 

 cumference of the mouth round both jaws is about three 

 feet. This animal is confounded with the white shark, 

 both by seamen and naturalists ; but it differs in the form 

 of its teeth, as well as in the other circumstances noticed 

 in the character. 



The colour of this species is deep bluish-black, and the 

 skin is smoother than that of most of its congeners. 



Sq. jnonensis, Beaumaris shark, first described by Pen- 

 nant, was by some considered as a sexual difference only 

 of the last ; but this is a mistake. Though similar in 

 many respects, they are quite distinct, as the following 

 characters, taken from a fine specimen caught in Orkney 

 in 1833, will show. The colour of the upper parts a pale 

 leaden gray, the lower parts yellowish white. Skin 

 above covered with very minute granular roughnesses, 

 but less prominent than in the Squalus catulus and Sq. 



' We liave already discussed the point above alluded to, at greater length, in a preceding portion of the present treatiae. See 

 p. 185. 



' The following are the more detailed measurements of the specimen above mentioned : — 



Inches 



Extreme length along curvature of back....« 3 



Girth at abdomen ' H 



.it spiracles J 



Width of mouth round upper lip 1 !) 



round lower lij) 1 4 



Length of teeth in upper jaw 1-5 



in lower jaw 1-2 



Length of muzzle from eye ^•b 



.^^^— . from upper lip 4-5 



Eye in diameter about 1 



Nostrils from eye 2 5 



Ijength of spiracles 9 



From snout to first dorsal 3 5'5 



From tlrst to second dorsal 2 6 



From second dorsal to caudal 



First dorsal, high, .ilong its edge 1 



perpendicularly 



broad 



Second dorsal, high 



broad 



Pectorals along edge I 



broad (• 



Caudal, upper lobe 1 



lower lobe 1 



spread 2 



Ventral at outer edge 



From pectoral to ventral 2 



Keel near tail 



Anal fin, broad 



lDChC8. 

 1 



10 



9-5 



1-8 



1-5 



5 



9 

 10-5 



3 







4 



4 



<»-5 



10 



