580 F. L. LANDACRE AND A. C. CONGER 



auditory vesicle grows backward and forms the lateral line. Locy 

 ('95) confirms in the type Squalus the observations of Wilson in 

 Serranus and Mitrophanow in Acanthias as to the common 

 primordium of the lateral sense organs and the auditory organ. 



On the other hand, a number of authors after making a care- 

 ful study of the relation of the lateral line system to the ear have 

 been unable even with the preceding results in mind to find any 

 genetic relation between the primordia of the lateral line organs 

 or the organs themselves and the ear. These results are espe- 

 cially significant in the light of the conclusions found in Lepidos- 

 teus, where the authors feel that they have not only demonstrated 

 that there is no genetic connection between the two but have 

 found ample grounds for explaining the contradictory results ob- 

 tained in other types provided they resemble Lepidosteus at all 

 closely. 



Miss Piatt ('95) cleared up much of confusion arising from the 

 investigations of former workers by making a sharp distinction 

 between the two series of placodes, dorsolateral and epibranchial, 

 on the one hand, and the early stages of the sensory lines on the 

 other hand. She. points out the fact that sensory lines may ap- 

 pear later in the exact place occupied by a placode or ectodermal 

 thickening, and further states that there is a resemblance 

 between the growing point of a placode and a lateral line organ. 



Miss Clapp ('99) does not trace the sensory lines in Batrachus 

 to the auditory vesicle or its derivatives, although she does state 

 that they originate in the region of the auditory vesicle. Dr. 

 Clapp's conservative statement is significant in view of the 

 amount of time she spent in an attempt to trace the lateral sen- 

 sory line and the auditory vesicle to the same primordium in 

 Batrachus. 



Miss Beckwith ('07) investigated the development of the 

 lateral line system in Amia from its first appearance up to the 

 first stage described by AUis ('89). She states that from her 

 observations 



It is evident that the lateral line anlagen do not arise in connection with 

 the auditory organ as described in teleosts (Wilson '91). The auditory 

 organ arises before the lateral line and independently of it, as an in- 



