1 6 HEMICHORDATA 



waste products discharged by the gland into the anterior body- 

 cavity, though this view is not favoured by Willey. 



Reproductive Organs. The sexes are separate, the repro- 

 ductive organs consisting of a series of simple or branched 

 glands which occur along the dorso-lateral lines of the anterior 

 part of the body ; being usually found throughout the branchial 

 and generative regions and ending at the beginning of the 

 hepatic region. The reproductive organs may pass into great 

 extensions of the body - wall known as the " genital wings," 

 specially developed in some species of Balanoglossus and Ptychodera 

 (Figs. 1 A, 4). 



Stereobalanus canadensis, a species with long slit-like external 

 gill -pores, is interesting in possessing a well -developed genital 

 wing both dorsal ly and ventrally to the series of gill-pores of 

 each side. 



Each reproductive gland opens by its own pore or pores 

 directly to the exterior. Several glands and pores may occur in 

 the same transverse section. 



According to Spengel there is no definite relation between 

 the number of the reproductive organs and that of either the 

 gill-sacs or the liver-outgrowths. The only definite segmenta- 

 tion exhibited by Balanoglossus is thus the division into three 

 regions which is so distinctly shown by the arrangement of the 

 body -cavities ; though the gill -sacs may indicate an incipient 

 further segmentation of the major part of the body. In this 

 connexion it is interesting to notice MacBride's statement T that 

 the body-cavity of Amphioxus develops in the embryo as five 

 cavities, just as in Balanoglossus ; the segmented part of the 

 body being formed by a secondary segmentation of the third 

 body-cavities. 



Regeneration. Balauoglossus, like Phoronis (p. 30), possesses 

 great powers of regenerating lost parts. The posterior part of 

 the body is readily re-formed, while Spengel has shown 2 that 

 even the proboscis, collar and branchial region can be regenerated, 

 apparently from a fragment of the body. 



Genera of Enteropneusta. Spengel, whose Monograph 

 is indispensable to every student of the Enteropneusta, formerly 



1 Quart. J. Micr. Sci. xl. 1898, p. 601 ; xliii. 1900, p. 351. 



2 Monogr. p. 684, PI. xxvi. Figs. 14-18 ; see also Willey, Zool. Res. iii. p. 245, 

 and Dawydoff, Zoolog. Anz. xxv. 1902, p. 551. 



