EAR-SWIMBLADDER RELATION IN CLUPEOIDS 231 



lip of the fenestra by very delicate connective-tissue strands which 

 are usually torn off in dissection. This band of tunica propria 

 and its overlying macular cells projects about equally over the 

 opening of the fenestra and over the posterior division of the 

 utricular subcerebral canal (fig. 17). The tunica propria of the 

 anterior division of the macula is thinner and band-like and is 

 loosely attached to the edge of the anterior fenestral lip. 



The anterior and middle divisions of the macula consist of 

 band-like areas of a two-layered epithelium (fig. 19). The basal 

 layer is composed of small cells with small round, dense nuclei; 

 the upper layer is of columnar cells, in which the cytoplasm 

 distal to the nuclei is densely granular and with indistinct cell 

 walls. Under the cuticulum of each cell is a small round, dense 

 body staining heavily with iron hematoxylin. Running out 

 from this body is a rather long cilium which is quite stout and 

 stains deeply near its origin. 



The anterior and middle divisions of the macula are sepa- 

 rated by only a slight interval and they lie in planes which 

 are nearly at a right angle to each other. Bridging across this 

 angle and connecting the two macular surfaces through the 

 endolymph, is a structure which in the early and adolescent 

 stages of development appears as a thick hyaline plate. In the 

 adult this plate has become transformed into an otolith by the 

 deposit of calcareous granules within it or on its upper surface. 

 Hence, I shall refer to the structure as the otolithic membrane 

 of the macula acustica utriculi. Its shape is determined by the 

 interval between the two macular divisions, and hence it forms a 

 long narrow triangle. Its apex is rounded mesially where the 

 two divisions of the macula unite; laterally it ends in a free edge. 

 The other edges spread out to cover the two macular surfaces. 



The middle part of this plate in the adolescent stages of 

 Stolephorus appears to be hyaline and structureless with the 

 exception of some horizontal striations. On each side of the 

 middle, the membrane appears to contain a great number of 

 cells or chambers like a honeycomb which end blindly toward the 

 middle of the membrane, but open onto the macular surfaces. 

 The plate undergoes much shrinkage during histological prepa- 



