212 APPENDIX. 



innervated distally, they correspond to the "Nervenknope" of Acerina 

 cermia, but Leydig (1879, p. 163) says concerning these that the con- 

 nective tissue of the swelHng, which surrounds tlie nerves and blood vessels 

 is tender, nearly gelatinous. It seems tliereforc that they do not belong to 

 the class of structures designated as "Nervenknopfe." The essential differ- 

 ence, the absence of a cylinder epithelium in the buds of Malthopsis, can in 

 so far not be relied upon, as it may be present in the living fish and absent 

 in the specimen examined only because it has fallen off on account of its 

 perishable nature ; the circumstances however that the organs are entirely 

 surrounded by a cuticle and that the tender and perishable sensitive epithe- 

 lium would, if present, be coverless and exposed, make it appear improbable 

 that such is the case. 



Concerning the physiological function of the organs it must be borne 

 in mind that they must either be radiating or sensory, because so rich an 

 innervation must have some purpose. The general appearance of the organs, 

 their semispherical shape and the abundance of connective tissue in them 

 are in favor of the latter view and make it probable that the function per- 

 formed by them is the perception of hydrostatic pressure, a knowledge of 

 which must be of great importance to any fish able to live only within cer- 

 tain bathymetrical limits. 



