EAR OF THE SQUETEAGUE. 1 221 



both sagittsE are pinned down the squeteague will still respond occasionally to 

 sound, but whether this response is through the sensory patch in the lagena or 

 even in the utriculus, or through the skin, can not be stated. That it is from 

 an organ far inferior to that in the sacculus is plain from its character, and hence, 

 though there may be other parts of the body of the squeteague than the macula 

 acustica sacculi that are sensitive to sound, this structure is certainly the chief 

 organ in this respect. 



It also seems fair to me to class the reactions of the squeteague to sound, when 

 these reactions are mediated by the ear, under the head of hearing. While no 

 sharp line can be drawn between touch and hearing, it seems to me that when 

 any vertebrate can be shown to possess an ear which is stimulated by the vibra- 

 tions of material particles it is fair to ascribe hearing to such an animal, and, for 

 reasons already given, I beheve this to be the case in the squeteague. I therefore 

 reaffirm my former statement that certain fishes can hear, a statement that 

 was based originally upon the conditions found by me in Fundulus heteroclitus 

 (Parker, 1903a, 1903b) and confirmed in certain respects in other fishes by Zen- 

 neck (1903) and in the goldfish by Bigelow (1904). It does not seem to me 

 that the very inadequate tests by Korner (1905) on some 25 fishes, with negative 

 results so far as hearing was concerned, as well as the similar results of Lafite- 

 Dupont (1907) can have great weight against positive results such as have 

 already been obtained by other investigators, for it is comparatively easy in 

 certain tests to find animals irresponsive to sounds by which they are certainly- 

 stimulated as shown by other methods (Yerkes, 1905). From the observa- 

 tions given in this section, I conclude that in the squeteague the sacculus with 

 its contained sagitta is the chief organ of hearing and that these parts have 

 nothing to do with equilibrium or muscle tonus. Although I agree with Hensen 

 (1904) in ascribing hearing to fishes, I believe, for reasons already given, that the 

 ears of these animals are also directly concerned with equilibrium. 



SUMMARY. 



1. The ear of the squeteague {Cynoscion regalis) is anatomically double in 

 that it consists of (i) a utricular organ with its semicircular canals and (2) a 

 saccular organ with its lagena. There is no utriculo-saccular canal. 



2. The utriculus possesses a macula acustica recessus utriculi covered by 

 an otolith, the lapillus, but no macula neglecta. Each of the three semicircular 

 canals has a crista acustica without an otolith. 



3. The sacculus possesses a macula acustica sacculi covered by a large oto- 

 lith, the sagitta, and the lagena has a papilla acustica lagense covered by a small 

 otolith, the asteriscus. 



4. Squeteagues whose eyes have been covered with blinders usually swim 

 with normal equilibrium. Squeteagues whose utricuU and semicircular canals 



