978 



ZOOLOGICAL . SOCIETY BULLETIN. 



This beer glass, brought up from the seaibottom, had 

 several boat-shells (crepidv.la) attached to it. 



rated groups arrangements for holding fast tem- 

 porarily by sucking discs have been evolved. In 

 the lowest group of fishes, the lampreys, there 

 is a sucking arrangement surrounding the mouth. 

 These fishes are temporarily parasitic upon other 

 fishes and the sucking apparatus contains the 

 mouth and piercing teeth or a rasping organ to 

 obtain food. 



The species known as sea-snails (Liparidae) , 

 lumpfishes (Cyclopteridae) and cling-fishes 

 (Gobiesocidae) have a sucking disc on the under 

 side of the thoracic region. In the sea-snail 

 and lumpfish this is an elaborate affair formed 

 by the modification of the united ventral fins. 

 In the cling-fish, these fins are separated and 

 the disc which lies between the fins is formed by 

 folds of modified skin. Some of the gobies 

 (Gobiidae) also have some ability for adhesion 

 by means of the united ventral fins. The sucker 

 enables these fishes to hold fast to rocks along 

 the shore without danger of being washed upon 

 the beach. Whether it may have other uses is 

 not known. So powerful is the grasp of these 

 sucking discs that the writer has lifted a stone 

 weighing a pound and a half by grasping a 

 three-inch fish which was attached to it, and 



some one records lifting a bucket of water by 

 means of a lumpfish fastened to the bottom of 

 the bucket. 



The remora or shark-sucker has on the top 

 of the head a sucking disc formed by the modifi- 

 cation of the first dorsal fin. This fish ordina- 

 rily attaches itself to the body of a shark or 

 other large fish, apparently for the purpose of 

 transportation, since it does the shark no injury. 

 It can swim rapidly, however, on its own ac- 

 count, and darts about to pick up scraps of food 

 when the large fish is feeding, or to capture 

 fishes too small to be of interest to the shark. 



One of the strangest examples to be found 

 among fishes is that of a South American cat- 

 fish inhabiting the mountain streams of the 

 northern Andes. This fish has a sucking ar- 

 rangement formed by an expansion of the under 

 lip. It is not only able to hold on by this disc, 

 but with the help of spines on the ventral fins 

 is able to make its way up vertical rock walls 

 past cascades. 



A CLING-FISH (Arbaciosa eos) 



The broad sucking disc is formed anteriorly by the ventral 



fins, and posteriorly by the skin of the belly. 



Enlarged twice. 



