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mechanism, it is necessary to subdivide them yet further into two 
secondary groups or “ divisions.” The first division includes 
all the expressive sounds of a harsh nature, and comprises, as 
far as the fishes of Europe are concerned, only one subdivision 
— that of stridulation, having for its cause the friction of the 
dental organs. Of souch sounds — “ bruits de stridulation ” — 
there are two modes of causation. 
a. By friction of the pharyngeal bones.* These noises are 
characterised by being composed of sonorous emissions, clear, 
short, rough and piercing, without flexibility or softness, and 
by commencing and ending abruptly (“ brusquement ”). The 
best example of this has been found in a species of mackerel, 
namely the “ Saurel ” (Scomber brachyurus , Linn.), known in 
the fish-markets of Paris under the name of 66 Maquereau 
batard,” and by that of u Severan ” on the coasts of old Provence. 
Both the males and females are equally sonorous, and especially 
so in the hottest part of summer ; and, moreover, present this 
advantage to the physiologist, that they will live for more than ten 
minutes — on rainy days for even sixteen or seventeen — after 
removal from the water, without seeming to suffer. M. Dufosse 
made several experiments with the saurel, and found that 
puncturing the air-bladder or other viscera had no influence 
on the sounds emitted, while, on the other hand, they entirely 
ceased when various substances, such as bits of kid glove, had 
been stuffed between the pharyngeal teeth — those dents-en- 
velours , as Cuvier termed them, which, like a gin, jealously 
guard the approaches of the gullet. It must be noted that the 
branchial arches differ from those of most of the mackerel 
family in having their mucous lining not clothed with a softish 
cartilaginous cushion, but encrusted inside with calcareous 
plates, and carrying tooth-like organs of the hardness of enamel. 
The various muscles, too, of the hyoidean apparatus (that which 
mainly influences the movements of the bones carrying the 
lower pharyngeal teeth) are relatively largely developed. It 
was further found that when the fish was examined in a vessel 
filled with sea-water, the sounds emitted were not accom- 
panied by the liberation of a single bubble of gas from any of 
the natural openings of the body, nor did the fish come to the 
surface to swallow the least mouthful of air. 
b. By the friction of densely hard prominences from the jaws, 
playing the part of intermaxillary teeth, noises being thus pro- 
duced which resemble the grinding of the teeth of pigs, or of 
certain ruminants. Only one fish is as yet known to employ such 
mechanism, namely the Sun-fish ( Orthragoriscus mola\ which 
* These hones are described and figured in an article, “How Fishes 
Breathe,” Popular Science Review, Oct. 1871. 
