I'l.KCTOGNATKS. 



(121 



ol' I lie I>i(iiliiii (Clii/dDn/ctenis) (ii/trint(ihis, wliicli was 

 i.iu^ht swiiiiiiiiiig lU'ar tho shore. Tliis tish is well 

 kiKiwn to possess the singular power of (listeiuliiig itself 

 inlii a iieai'l\ spherical form. Alter iiaNiiiii' been taken 

 out of watei' for a siiort time, and then again ininierse<l 

 ill it. a eonsiderable ipiantity liotii of water and air is 

 ahs(irl)ed hy the nioiitii, and perhaps likewise by the 

 branehial oriliees. This process is effected by two meth- 

 ods; the air is swallowed, and is then fui'ced into tli(> I 

 cavit\- of the body, its return being prevented by a 

 niusciilar contraction which is I'xternajly visible; but 

 ihe water, I iibserved, enters in a gentle stream through 

 the niiiiitli, which is kept wide open and inotioidess: 

 this latter action nuist. therefore, depend on suction. 

 The skin about the abdomen is nuieh looser than that 

 (III the back; hence during the inflation, the lower sur- 

 face becomes far more distended than the iijiper; and 

 the fish, in conse(|uence, floats with its back downwards. 

 ("r\ii;i; doulits whether the Dliuhni in this position, is 

 able to swim; but not onl\' can it thus move forward 

 in a straight line, but it can turn round to either side. 

 This latter movement is effected solely by the aid of 

 the ))ectorul tins, the tail being collapsed, and not used, 

 from the bod\ being buoyed U|) with so much air, the 

 branchial i)]ienings were out of water; but a stream 

 drawn in b\- the mouth constanth' Hows through them. 



"The tish, having remained in this distended state 

 fill- a short time, generally expelled the air and water 

 with considerable force from the branchial apertures and 

 imiiiTh. It could emit, al will, a certain portion of the 

 water; and it a])]iears. therefore, probable that this 

 fluid is taken in parth- for the s.-ike of regulating its 

 specific gravity. 



"This Diodoii |)ossessed several means of defence. 

 It could give a severe bite, and could eject watei' from 

 its month to some distance, at the same time making a 

 curious noise bv the movement of it^ jaws. ISv the 

 inflation of its body, the papilhe. with ^\•hich the skin 

 is covered, become erect and pointed. But the most 

 (•nrious circumstance is, that it secretes from the skin 

 of its belly, when handled, a most beautiful carmine-red 

 fibrous matter, which stains ivory and paper in so per- 

 iiiaiieiit a manner, that the tint is retaine<l with all its 

 lirighiiiess to the jiresent da^'. I am (piite ignorant of 

 the nature and use of tliis secretion. I have heard 



from Dr. Allan of f'orres, that he has fre(|uentl\' I'ouikI 

 a Diodon, floating alive and distended, in the stomach 

 of the Shai-k; and that on several occasions he has known 

 it eat its wa\-, not oiil\- through the coats of the sto- 

 mach, but througli the sides of the monster, whicli has 

 thus been killed. Who w<iuld ever ha\e imagined that 

 a little soft tish could liaxc destroved tiie great and 

 savage Shark?" 



The power here mentioned b\- 1)ai!W1n, that of pro- 

 ducing sounds, is one of the faculties highly characteristic 

 of these fishes. The Plectognates have long been known 

 as the most assiduous musii'iaiis of the ocean. Now it 

 is the jaws, now the articidar siu-faces of tlie spinous 

 ravs in tlu; dorsal or ventral fins, where these fins con- 

 tain such rays, that make a snapping, ringing, grating, 

 or laughing noise"; now it is the hissing sound of water 

 and air driven out of the bod\'; now it is the air- 

 bladder whose vibrations may be distinctly heard like 

 the beating of a drum*. For this purpose the air-bladder 

 is attached, in the drumming Balistoids, to the shoulder- 

 girdle on each side and to s]jecial, large dermal plates 

 just abo\'e the iijiper angle of the pectoral fin. By the 

 (|uivering mo\<'meiits that accompan\' the violent con- 

 traction (cf. above, \). 198) of the venti'al parts of the 

 lateral muscles, the po.stclavicular bones, which are in- 

 serted in these muscles, are set in a vibrating motion 

 which is transferred to the wall of the air-bladder and 

 to the air contained therein, from which the sound is 

 transmitted to the said osseous plates in the skin above 

 the angle of the pectoral fin, and through their medium 

 to the outer world. All the snapjiing, ringing, grating, 

 laughing, or hissing sounds are probably intended, here 

 as in other fishes Avhich have this power, in the fir.st 

 place to frighten away some approaching foe. The 

 notes or drumming noises of the air-bladder raa\- also 

 conduce to the same result, or mav be produced by 

 the death-throes of the fish. But, as SoREXSEX has 

 remarked, the sonorous tones that compose the song 

 of these fishes, undoubtedly serve in other cases, espe- 

 cially during the si)awning-season, as call-notes. 



Cuvier' divided the Plectognates into two families, 

 the first with free teeth in the jaws and usually with 

 hard (plate-like) dermal covering — hence the name of 

 /e.s Srlerodnrmcs, from o^/iipo-, hard and ()*'?'"■'. skin 

 — the second with the jaw-teeth confluent and forming 



" Cf. SiiRE.NSE.N, Oni Ln-lnnjiinn- hos Fixke, Kjobeiiliavn, 1884. 



" Cf. MuBius, Baliste." nnileatn.^. eiii trommelnder Fi>si-h, Stzber. kk>x<i. Wiss. BerL 1889, \u 999. 



' Regne Animal, e,L 1. tcni. II. pp. 14.0 anii 149; ed. 2. torn. II, pp. .'ifi.^ and 371. 



