ANATCij\lY OF APENICOLA ASSIMILIS. 779 



8. Post-larval specimens of A. assimilis, var. affinis^ are 

 described from the Falkland Islands. They possess an 

 achastous segment between the peristominm and first 

 chfetigerons segment (as in similar stages of A. marina and 

 A. ecaudata). By comparison with the adult the limits in 

 the latter of the peristominm and achfetons body-segment 

 may be determined (figs. 19^ 20). 



9. Adult specimens of A. assimilis, var. affinis are also 

 described from Stanley Harbour, East Falkland. They are 

 remarkable for the large size of their otocysts, the internal 

 volume of which is about four times that of tlie otocysts of 

 the Otago specimens (figs. 14, 15). It is evident that a con- 

 siderable variation in the size of these orgaiis may occur in 

 specimens of the same species or variety from diiferent 

 localities. The otoliths, several of which contain an irregulnr 

 foreign body, are spherical, and in one specimen two of them 

 are much larger than any of the others. They are the first 

 two otoliths of the post-larval stage which have continually 

 received fresh depositions of secreted substance, and always 

 remain distinguished from those formed later by their lai^ger 

 size. These specimens from the Falklands differ from the 

 Otago specimens in the nature of their otoliths. Here is 

 additional evidence that the character of the otoliths con- 

 tained in otocysts provided with a tube leading to the 

 exterior is not a feature upon which much value should be 

 placed in systematic work. Blocking of the tube (as occurs 

 in the Falklands specimen) converts the otocyst into a closed 

 sac, in which spherical otoliths are formed, while in other 

 specimens (e. g. those from Otago Harbour) in which the 

 tube remains open the otoliths ai-e irregular foreign bodies, 

 such as sand-grains, which are able to gain access to the 

 otocyst. 



10. Ehlers records A. assimilis from the Straits of 

 Magellan, the Beagle Channel, South Georgia, Chile 

 (Schmarda), Kerguelen (Griibe), and California. It is shown 

 that there is no evidence in support of the last three 

 recoi'ds. Schmarda's and Grube's specimens are insufficiently 



