200 



K. MITSUKUIU : STUDIES ON 



convinced me tliat, for the present at least, the two genera should 

 be kept apart. When a dorsal ambulacrum is looked at from the 

 inside, there is in La'tmogone only one series of ambulacral 

 vesicles on the outer side of the said ambulacrum ; while in 

 Ilyodo'inon there are two series of these vesicles, one on both the 

 outer and the inner sides of the ambulacrum. 



46. Ilijoda'Uioii ijhnni Mitsukiki. 

 (n. YI., %. 55; textfis. 37). 

 Ilyodonmon ijimai MiTsrivi'm 1897/*, ]>p. 133 — 5. 

 Specimens examined : — 



