E. OWENI. — GEN. CHAKACTEES. 207 



The compressed, inferior eud is normally closed by a hotlom- 

 flate. The apparent absence of this in some specimens is probably 

 due simply to damage after capture. It is of essentially the same 

 appearance as that of E. marshallL The same holds true of the 

 strongly arched, often hemispherical sieve-plate of the superior 

 end as well as the portion of the basal tuft nearest its point of 

 origin. The occurrence of the bottom-plate and the condition 

 of the basal tuft indicate that the mode of insertion of the 

 species into the substratum is likewise the same as in E. marshalli 

 (p. 93). 



In many specimens the basal tuft is present as a clean, 

 silky lock of considerable length. As more normal are to be 

 considered the cases in which I have found the tuft form, a 

 short distance below the point of its origin, a bulky, irregular 

 or elongate mass, including a copious quantity of sand, shell- 

 fragments, worms-tubes, &c. 



Parietal ledges and the euff have been hitheito considered 

 to be entirely wanting in the present species. I must say that 

 such is not always the case ; in fact, both the structures men- 

 tioned seem to be of common occurrence, though they are never 

 so prominently or so extensively developed as in E. marshalli. 

 Here again it seems we have to do with a character which is 

 subject to considerable variation according to individuals. 



The beautifully preserved specimen I have shown in PI. VI, 

 fig. 4 (J of the list on p. 205) approaches most closely to the 

 descriptions given by Marshall and Schulze in respect of the 

 character of the external surface. In it, the parietal ledges are 

 at most simply suggested, the interspaces between th(3 parietal 

 oscula having in general a gently convex, external surface. 



