ZOOLOGICAL SOCIETY BULLETIN 



279 



be artit'ically produced on a deail fish l^y manipulat- 

 ing the parts concerned. Striduhition is not con- 

 fined to one species of fish but has been heard in 

 animals of widely separated families. The harsh 

 noise produced by the rubbing together of the 

 pharyngeal teeth in one species of mackerel and by 

 the grating of the "incisor" teeth of the putTcr or 

 swell-tish might also be classified under slridu- 

 lation. 



In certain fishes whose air-bladder opens by a 

 duct into the digestive tract (stomach or oesophagus) 

 a noise is made by the forcing of gas from the air- 

 bladder through the air-duct {ductus piieumaticus) 

 and mouth. Noises are produced in this manner 

 by the eels, the carp, and certain loaches and are 

 frequently spoken of as breathing sounds, although 

 in no way connected with the phenomenon of 

 respiration. 



The drumming noises made Ifv many of the Sci- 

 anidcc, such as the drum, the weakfish (Squeteague), 

 and the croaker, are produced by a unique, special- 

 ized muscle which undoubtedly has been developed 

 for the purpose of producing sound. This muscle 

 with its tendons forms a closed cavity in which is 

 contained the air-bladder and remaining abdominal 

 organs. By the contraction of this muscle all of the 

 abdominal organs are made to vibrate, especially 

 the air-bladder. The vibrations are of such a 

 character as to make a low sound which under the 

 rapid contraction of the drumming muscle produces 

 the effect of a roll on a drum. In most of these 

 fishes it is only the male that possesses the special 

 muscle and consequently only the males make the 

 noise. The drumming can be readily observed in a 

 male squeteague placed in a small aquarium and 

 under the proper conditions. The drumming of a 

 weiikfish can be distinctly heard many feet away, 

 and if removed from the water the noise can be 

 easily recognized thirty or more feet distant. It is 

 undoubtedly a call of one fish to its mates. 



.\ noise which is best described as a grunt is 

 produced by many fishes of the family Triglida, 

 the most common examples being the red-winged 

 sea robin and the toad-fish. These animals pos- 

 sess a more or less two-lobed air-bladder which 

 is equipped with two muscles, one on each lobe. 

 These muscles apparently form part of the wall of 

 the air-bladder, and by their contraction the wall 

 is made to vibrate in such a way as to produce a 

 single distinct grunt. Often when a toad-fish is 



taken from the water in a net, the grunt made by 

 this animal will be heard some distance away. 

 The same noise can be jjroduced artificially by 

 stimulating the muscle with an electric current soon 

 after the death of the animal. 



Among the Siluridte or catfishes is found still 

 another apparatus which some consider to be a 

 mechanism for the production of sound. The 

 transverse processes of the fourth vertebra are 

 extended backward, ending in bony plates cm- 

 bedded in the front part of the air-bladder. These 

 processes, which thus form elastic springs, are con- 

 nected with the head region by two powerful 

 muscles. By the contraction and relaxation of these 

 muscles the air-bladder is set into vibration, which 

 produces a sound. 



That certain fishes do produce characteristic 

 sounds which undoubtedly serve a distinct purpose 

 to the animal is a fact which has been pro\-ed by 

 observation and experiment and can be verified 

 with comparative ease. Much, however, remains 

 to be learned about this verv interesting subject. 



THE SUNAPEE TROUT. 



THE Aquarium recently received several s[)eci- 

 mens of the beautiful golden trout of Sunapee 

 Lake. 



This species, known at Sahcliuus aureolus, is 

 found only in Sunapee Lake, N. H., Flood Pond, 

 Me., and other lakes in that region. Since it was 

 described as a new species a few years ago, it has 

 been introduced into other lakes. 



It is a trout of large size, known to have reached 

 a weight of eight pounds. The Aquarium specimens 

 are about eighteen inches in length. It remains 

 habitually at considerable depths, where the water 

 has a temperature below fifty degrees, and is taken 

 chiefly with live bait. 



The specimens in the Aquarium, which appear to 

 have lost color since their arrival, are of a pale 

 brownish color above, the head being lighter, and 

 the sides have faint orange spots. The entire 

 under surface, including the tins, is of a pale orange 

 color. The front edges of the fins are broadly 

 margined with white. 



The species is so closely related to the European 

 char that it may have been introduced into this 

 country. It was not known to anglers until about 

 twentv-five vears ago. 



