984 FISHES — COTTIDJE. 



species is peculiarly liable to the attacks of parasitic entozoa, and great 

 tumors are often found on difiereint parts of the body. 



In the lakes of Northern Indiana it is known as Crocus, which name 

 is a corruption of Croaker, a name given to species of the marine genus 

 Micropogon in the same family. In the Ohio River it is now usually 

 known by the name of White Perch, and commands a good price, al- 

 though compared with the Sun-fishes and Bass, it is very indifferent 

 food, not better than Suckers, except that the bones are fewer. Farther 

 south it has the name of Drum, which term is also applied to the species 

 of the related marine genus, Pogonias. 



The names Croaker, Drum, Grunter, Thunder- pumper, etc., refer to a 

 croaking sound, which the fish makes when in the water, and which 

 may be heard in the night by putting the ear close to the water in still, 

 deep places in rivers inhabited by this species. 



This phenomenon is found in all or most Sciasnidx, and in many of the 

 related families, Sparidas, Cottidse, etc. It is always accompanied by a 

 trembling of the sides of the fish, very perceptible when a fish recently 

 taken is held in the hand. It is thus explained by Dr. Holbrook (Ichth. 

 S. Car., 118), in the case of the salt water Drum {Pogonias chromis). 



" Cuvier observes that it may depend on tMe air-bladder. Thongh he says that it has 

 no connection with the ontside atmosphere. DeKay supposes it to be occasioned by the 

 strong compression of the expanded pharyngeal teeth on each other. 



"Frequent examinations of the structure and arrangement of the air-bladder, as well 

 as observations on the living animal just taken hom the water, when the sound is at in- 

 tervals still continued, have satisfied me that it is made in the air bladder itself; that 

 the vibrations are made by the air being forced by strong muscular contractions through 

 a narrow opening from one large cavity, that of the air-bladder, to another, that of the 

 cavity of the lateral horn ; and if the hands be placed on the sides of the animal, vi- 

 brations will be felt in the lateral horn, corresponding with each sound." 



It seems to me certain that the noises proceed from the air-bladder, but it is also cer- 

 tain that they are produced in some species (Artedius, etc. in which the air-bladder has 

 but one cavity, and is without the complicity of structure found in Pogonias and most 

 Soiemoids. 



The ear bones in Haploidonotus grunniens are largely developed, quadrate 

 in form, and marked with a rude impress of a letter L. These are com- 

 monly known as " lucky stones " to boys living where this fish is found." 



FAMILY XXIV. COTTIDiE. THESCULPINS. 



Body moderately elongate, fusiform or compressed, tapering backward from the head, 

 which is usually broad and depressed; eyes placed high, the interocular space usually 

 narrow ; a bony stay connecting the suborbital with the preopercle, usually covered by 



