246 



CLAPP. 



[Vol. XV. 



appearance of the commissures connecting the ganglia of the 

 sympathetic system, and from the fact that it resisted the action 

 of nitric acid I inferred that it was nerve tissue. In direct sun- 

 light, by aid of an ordinary lens, this cord was plainly to be 

 seen, and its connection at either end with the cells near the 

 summit of the sense organs was evident. 



The appearance of this structure in connection with a free 

 organ is shown in a section from the side of the body of a 

 specimen 10 cm. in length (Fig. 16, cott.st.). As may be seen, 

 the strand near the organ has a diameter greater than that 

 of the nerve supplying the organ, and it extends in a sort of 

 festoon from the summit of one organ to that of the next in 

 the line, becoming narrower midway between the organs. It 

 extends below the skin into the thick felt-like layers of connect- 

 ive tissue occupying the space between the skin and the mus- 

 cles. This cord is also found connecting the organs of the 

 supra- and infraorbital lines in the head, as well as those of 

 the operculo-mandibular line, and even where free organs seem 

 quite disconnected, as in case of organs on the top of the head, 

 there is at least a short extension of this cord on each side 

 of the organ. In Figs. 22 and 23, the strand is represented in 

 blue. A cord of cells is found on the floor in the epithelial 



lining of the canals 

 (Figs. 22 and 23). It 

 therefore becomes 

 evident that in the 

 case of Batrachus tau 

 the connecting strand 

 constitutes a promi- 

 nent feature through- 

 out the lateral line 

 system in the adult 

 fish (Cut 5). Boden- 

 stein (9) describes 

 this structure in the adult Cottus gobio, and says that the 

 strand extends from the center of one organ to the next. This 

 is hardly the case in Batrachus (Fig. 16), as the cord evidently 

 terminates at the summit of the organ, among the supporting 



con. St. 



Cut 5. 



-A cross-section of temporal canal of Batrachus, 

 showing the strand in floor of canal. 



