370 MYZOSTOMEA. 



of segments in the formation of the feet and setas, the larva of the Myzo- 

 stomea shews an approximation to the Cheetopoda, and the group is 

 probably to be regarded as an early Chaetopod type specially modified in 

 connection with its parasitic habits. 



BIBLIOGRAPHY. 



(379) L.Graff. Das Genus Myzostoma. Leipzig, 1877. 



(380) E. Metschnikoff. "Zur Entwicklungsgeschichte d. Myzostomum." 

 Zeit.f. wiss. Zool., Vol. xvi. 1866. 



(381) C. Semper. "Z. Anat. u. Entwick. d. Gat. Myzostomum." Zeit.f. wiss. 

 Zool., Vol. ix. 1858. 



GASTROTRICHA. 



A few observations of Ludwig on the winter eggs of Ichthydium larus 

 shew that the segmentation is a total and apparently a regular one. It 

 leads to the formation of a solid morula. The embryo has a ventral 

 curvature, and the caudal forks are early formed as cuticular structures. By 

 the time the embryo leaves the egg, it has almost reached the adult state. 

 The ventral cilia arise some little time prior to the hatching. 



BIBLIOGRAPHY. 



(382) H. Ludwig. " Ueber die Ordnung Gastrotricha Metschn." Zeit. f. wiss. 

 Zool., Vol. xxvi. 1876. 



