ZOOLOGY. 613 



system in the adult state." This conclusiou, it is held, adds " proba- 

 bility to the view of Gegeubaur that the pronephros is the primitive 

 excretory gland of the Chordata (i. e., tlie Vertebrates and Tunicates); 

 and that the mesonephros or WolflSan body, by which it is replaced in 

 existing Ichthyopsida, is phylogenetically a more recent organ." 



Ecliiodon and Tetrogonurus commensal fishes. 



Professor Emery, as new ''Contributions to Ichthyology," has recorded 

 the fact that the Ecliiodon dentatus (or Fierasfer dentatus) forces itself 

 upon Holothurians as a guest, like the typical Fierasfer. A small speci- 

 men of the species"was found in a Holutlmria nehulosa at Naples in the 

 summer of 1881. 



Professor Emery also found three young specimens of Tetragonurus 

 cuvieri in the respiratory cavity of a large Salpa caught in the Gulf of 

 Naples in the spring of 1880. It has been stated that young Tetrogo- 

 nuri also associate with Medusae. (See Giinther's Introduction to the 

 Study of Fishes, p. 501.) 



The electrical organ of the Electric Eel. 



The electrical organ of the South American Electric Eel — Electro- 

 phorus (or Gymnotus) electriciis— has been studied by Dr. G. Fritsch, and 

 his results are described in the great work of Sachs and DuBois Rey- 

 mond on that fish. That the electric organ is developed from striated 

 muscle is evident, inter alias, from the fact that a common fascia sur- 

 lounds the organ and inferior lateral muscles ; the electric organ, in 

 fact, is the modified superior muscle. It is also noteworthy that there 

 is a remarkable variation in the number of electrical columns, a range 

 between 50 and 100 occurring. The Electric Eel thus contrasts markedly 

 with the Torpedo, in which the number of columns is constant for the 

 species. (J. E. M. S. (2), v. 2, p. G02.) 



Determining cause of the coastivard movement of the Herring. 



The movements of the Herring coastward, concerning which there has 

 been so much siieculation, is believed by O. J. Broch to result from the 

 assemblage of the small animals on which it feeds in the summer and 

 autumn. These animalcules live in immense numbers at or near the 

 surface, and their distribution is supposed to be regulated chieily by 

 the predominant winds and currents. The course of the Herring toward 

 the coast in the spawning season will therefore depend on the locality 

 of the last feeding grounds. 



Mortality among the Tile-fish. 



The remarkable history of the Tile-fish closes, for the present, with 

 an extraordinary climax. This fish, the Lopholatilus chamccleonticepSj 

 a species sometimes attaining a weight of 50 pounds, or even more. 



