274 MEAD. [Vol. XIII. 



divide bilaterally (cf . Ampkitrite, Cljmenella, Nereis, etc.), with- 

 out exhibiting a trace of the alternating oblique cleavage. 

 Other anomalous divisions occur in the cells corresponding to 

 the primary prototroch of Ampkitrite and Clymenella. Figs. 

 131, 132 show the cleavage of one of these cells, and I have 

 seen others divide. 



Wilson '' described the larva of this form as having no proto- 

 troch. See also Korschelt and Heider.^ It is possible that 

 there is some correlation between the anomalous behavior of 

 the trochoblasts and the absence of the prototroch. 



^ E. B. Wilson: Observations on the Early Developmental Stages of Some 

 Polychffitous Annelids. Stud. Biol. Lab. Johns Hopkins Univ., vol. II, 1882. 

 8 Korschelt und Heider: Lehrbuch der Entwicklungsgeschichte. 



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