1 88 AYERS AND JACKSON. [Vol. XVI I. 



Parker and Haswell's statement that the genital products 

 make their exit by the genital pores is not true of the myxi- 

 noids, for their eggs and spermatozoa both leave the body 

 through the abdominal pore. 



On page 129 it is stated that "the slime glands of Myxine 

 contain peculiar thread cells, containing a much coiled thread 

 which unwinds either before or after the discharge of the cells 

 from the gland." 



Under normal conditions the thread cell never unwinds until 

 it is extruded from the glands ; for its unwinding is due to the 

 absorption of water by the thread and is a hygroscopic function 

 entirely. The thread filament constitutes almost the entire 

 mass of the oval spool. 



The statement that " the branchial basket in the myxinoids 

 is reduced to a vestige," that "it is quite rudimentary, being 

 represented in Bdellostoma only by a small, irregular cartilage 

 in the walls of the oesophago-cutaneous duct, and in Myxine 

 by a smaller cartilage on the right side supporting the com- 

 mon external gill tube," is, as we shall see further on, due to 

 the failure of Miiller and subsequent anatomists to find the 

 major part of the branchial skeleton. Every gill in Bdellos- 

 toma is provided with a branchial cartilage. 



On page 130 the statement that "the neural canal is over- 

 arched merely by fibrous tissue ; there is no trace even of the 

 rudimentary neural arches of the lamprey," is far from the 

 truth, since we have discovered that Bdellostoma possesses a 

 true neural arch as a part of its axial skeleton. 



As regards Johannes Muller's descriptions of the muscles of 

 Bdellostoma, we find them inadequate in many cases, since he 

 failed to carefully trace out the forms of the muscles ; and in 

 other cases he failed to see the true homologies, and thus 

 necessitated the changing of several names. 



The erroneous statements in myxinoid anatomy which we 

 have pointed out above are certainly sufficient to render neces- 

 sary a careful reexamination of the whole subject, and upon 

 such a work Dr. Ayers has been engaged since 1892. 



During the past year Mr, C. M. Jackson has taken part in 

 a final review and careful redissection of Bdellostoma, with 



