490 A. J. MASTERMAN. 



it. Perhaps it would be as well to state once for all that the 

 trunk has no nephridia and possesses no normal openings till 

 after the metamorphosis. 



In reference to the oral and " pharyngeal " (? atrial) grooves 

 the author speaks of a " grave error " into which I fell by 

 not examining the living larvae. With all due deference to 

 him I must state that the existence of these grooves first 

 appeared to me by experimental feeding of the living larva. 

 Indeed, the course of food and water currents indicates their 

 presence far more clearly than does their structural differen- 

 tiation. In feedings the larva places the preoral hood well 

 down, and the food particles pass upwards along the ventral 

 surface of the collar (not of the hood, as wrongly quoted by 

 Ikeda, p. 536) in two slight depressions, indications of which 

 are also seen in sections (fig. 29). On the other hand, the 

 atrial water passes in a stream along the line of junction 

 between hood and collar and out at the dorsal edge of the 

 collar. These atrial grooves are also more in physiological 

 than morphological evidence, though ray sections show that 

 there is a groove between hood and collar. (Woodcut 5, on 

 p. 301, should sufficiently explain this.) Lastly, the author 

 remai-ks, " Masterman has made the statement that in its 

 natural attitude the hood had its length disposed parallel to the 

 principal body axis. However, if the larva be examined in 

 the living state, it will at once be discovered that its normal 

 disposition is horizontal" (p. 536). The actual statement 

 was, " The hood is in the position which pei'haps may be 

 described as normal " (p. 289), which is not by any means 

 the same thing. Actinotrocha spends most of its time 

 with the hood flexed ventrally, but the extension of the hood 

 forwards is effected at pleasure and usually with great 

 frequency. The term " normal " was used in much the same 

 sense as one would regard the proboscis of the nemertine, when 

 extruded, as being in the normal position, or the extended 

 arm of the human subject. A little careful study of the 

 work which he contradicts would have enabled Ikeda to 

 avoid these seeming discrepancies. In addition to Ikeda's 



