The Arcnicolidce of Suutli Africa. 



19 



about 2 mm. Posteriorly and laterally the prostomium is bounded 

 by the nuchal organ. 



Each of the specimens has nineteen chtetigerous segments. The 

 neuropodia of the branchial region form oval or nearly semicircular 

 pads on the lateral region of the segment, but neither the muscular 

 ridge nor the groove, or sac, which contains the crotchets, ap- 

 proaches the mid-ventral line. Short neuropodia of this type are 

 found only in the species A. assimilis and A. claparedii Levinsen. 



The setiB of this species do not present any striking features such 



P 



TEXT-FIGURE IV. 



Arcnicola assimili*. Anterior end, 

 dorsal aspect, of a specimen from 

 Uschuaia, Beagle Channel. The pro- 

 stomium is shown in a state of normal 

 extension, x 6. 



TEXT-FIGURE V. 



Areiiicola assimilis var. a (I'm it. An- 

 terior end, dorsal aspect, of a specimen 

 from the Falkland Islands. The pro- 

 stomium is shown protruded to its 

 fullest extent, x 6. 



L. Lateral lobe of prostomium. M. Median lobe. N 1 . First notopodium. 

 P. Median posterior portion of prostomium. PH. Pharynx. S. Aperture of stato- 

 cyst (which is shown too large in the figure). 



as those met with in A. lorcni. The notopodial and neuropodial 

 setae are similar to those of A. marina. 



All the specimens from Liideritzbucht have the full complement 

 of gills, namely, thirteen pairs. The first gill is borne on the seventh 

 segment and is invariably of moderate or large size. In the 

 examples from Table Bay, the first gill exhibits very marked re- 



