103 



This action is so quick as to be scarcely perceptble. It is 

 accompanied by a rather loud sound, like the drawing of a 

 cork or a rap, which can be heard through the inch-thick glass 

 at any place in the tank-room. This sound is not produced by 

 the teeth of the fish, which are very minute and can scarcely 

 be felt by the finger. 



An incident which throws a significant side-light on the 

 habits of the Horse-fish was observed on the introduction of a 

 rather large hermit crab, which a fisherman had found without 

 its shell and brought to the aquarium as an " English Lobster." 

 When placed in the tank the Horse-fish made for it at once ; 

 the crab at the same time recognised an enemy ; it bent its 

 exposed abdominal part quite under the harder carapace and 

 faced the fish, W'hich endeavoured to get behind it. The 

 action of both fish and crab was so prompt and purposeful that 

 it could not but be concluded that they were both familiar with 

 the results of being caught without a shell. 



The Horse-fish made no attempt to catch the small fish, 

 which were often around and near it in numbers, but on one 

 occasion it was observed to seize a small cuttle-fish {Sepia 

 verrucosa). 



Though the Horse-fish will not at first take anything but 

 crabs, like most other fish it soon learns to take the usual food 

 supplied in the tanks — pieces of fish flesh. It was never 

 observed to take " red bait," so greedily seized by most other 

 fish. 



Another and smaller species of Horse-fish {A. spinifer) is 

 sometimes procured for the tanks. It is, in general shape and 

 appearance, somewhat like the larger form, but has a spine 

 just below and in front of the eyes. The fish, when first pro- 

 cured, was healthy and more lively than A. torvus, but gradu- 

 ally fell off, refusing to eat the food offered it. A large piece 

 of " red bait " was put into the tank and it immediately began 

 to show a keen interest in this, peering into the cavities and 

 examining the whole in the same close way as the large Horse- 

 fish. Shortly afterwards it was observed picking out small 

 Crustacea and worms and, a few days afterwards, being supplied 

 with this food, it quite recovered its normal appearance and 

 lived for about two years in the tank. 



After a time this fish also learned to take pieces of fish flesh, 

 and soon began to watch the keeper for food, as the other 

 fish did. 



It is the only fish which has been observed to cast its skin. 

 This occurred in the winter time in July. The process is 

 rather rapid ; thus, in one case, in about three days from the 

 time the shedding began, the skin was observed to be hanging 



[C.P. 6-'i4.] 



