190 GIANT FISHES 



fins are normally shaped, so that we pass straight on to s. Our 

 shark fits all the characters given under s, so that we then 

 know that we are dealing with a Greenland or Sleeper Shark 



I. There are 5 to 7 external gill-openings on each side 

 (Selachians). 

 a. The external gill-openings are on tne sides of the head, 

 the last being in front of or above the base of the 

 pectoral fin ; the front edge of the pectoral fin is 

 free (Sharks). 

 b. There is 1 dorsal fin ; there are 6 or 7 external 

 gill-openings on each side. 



c. There are 6 external gill-openings on each side 



Six-gilled Shark or Griset (p. 5). 

 cc. There are 7 external gill-openings on each side 



Seven-gilled Shark or Perlon (p. 5). 

 bb. There are 2 dorsal fins ; there are only 5 external 

 gill-openings on each side. 



d. An anal fin in present. 



e. The eye has no third eyelid or nictitating 

 membrane. 

 f. There are no grooves connecting the mouth 

 with the nostrils ; all the gill-openings are 

 placed in front of the pectoral fin or the 

 last is just above its root. 

 G. The upper lobe of the caudal fin is less than 

 one-third of the total length of the shark. 

 H. The tail has no keel ; the caudal fin is not 

 symmetrical ; the second dorsal fin is 

 nearly as large as the first. 

 1. The lower lobe of the caudal fin is 

 distinct ; the snout is short ; the 2 

 dorsals, the anal, and the pelvic fins 

 are all nearly equal in size 

 Sand Sharks or Slender-toothed 



Sharks (p. 7). 

 11. The lower lobe of the caudal fin is not 

 very prominent ; the snout is long ; 

 the dorsal fins are smaller than the 

 anal or pelvics 



Elfin 01 Goblin Shark (p. 9). 

 hh. There is a marked keel on each side of 

 the tail ; the caudal fin appears more 

 or less symmetrical ; the second dorsal 

 fin is much smaller than the first 

 j. The external gill-openings are of 

 moderate size ; the teeth are large. 



