Spawning-hoMls of the Pilot Fish. 115 



throw light on some peculiarities in the behaviour of the 

 fish. 



The pilot fish is not uncommon in the Cape seas. The 

 young are frequently abundant in the summer months, 

 being found in company with the young of Lichia amia, 

 which they somewhat resemble in the characteristic markings 

 of the body. The adults are well known, under the name 

 " Lootsman," to Cape fishermen, who state that they are 

 always found accompanying a large shark, called the "Tor- 

 nijn Haai '' or porpoise-shark {Charcharias melanopterus). 

 They take up a more or less constant position near the body 

 of the shark, and remain within a few inches of the base of 

 the pectoral fin. The fishermen have also noted that they 

 liave the habit of darting away from the shark towards any 

 strange object, and then returning to their former position. 

 This well-known behaviour, interpreted in other parts of 

 the world as a guiding or piloting of the shark to its food, 

 the Cape fishermen believe, is for the purpose of a preliminary 

 tasting or testing of the food on behalf of the shark. 



On one occasion, in the month of December, a specially 

 large pilot fish was caught on the hook by some fishermen 

 fishing off Cape Point. It w^as in the company of a porpoise- 

 shark. By placing the fish in a bucket of water, it was 

 possible to keep it alive, and convey it to the Marine 

 Laboratory at St. James, where it Avas placed in a large 

 tank, and seemed none the worse for its capture. It proved 

 to be a mature female with ripe eggs, which were extruded 

 on slight pressure. 



These extruded eggs were readily seen, being large, though 

 quite transparent. When placed in water, however, they 

 became almost invisible. They did not float, and they 

 adhered to each other and to objects with which they came 

 in contact. The shape of the eggs was distinctly oval, 

 though a few were more rounded. A typical example, shown 

 in the accompanying figure (p. 116), measured 1*74 mm. in 

 length and 1*3 mm. in greatest breadth. In another case 

 the measurements were 1*65 x 1*39 mm. There were very 

 minute dots on the surface of the egg, and from one pole 

 originated a single fine filament. This was of considerable 

 length, being in one case six times the length of the 

 egg, or about 10 mm. In most cases it was shorter, 

 and in some it appeared to have broken off close to the egg. 

 The filaments readily became entangled with each other, so 

 that it was difficult to separate out any particular one with- 

 out breaking it. At its base the filament had a broad 

 attachment to the outer membrane, of which it is apparently 



