220 TRANSACTIONS OF THE [mAR. 8, 



in outline, constricted near insertion of cirrus. Two acicles, 

 equal number of bristles from each. Ventral cirrus half as long 

 as dorsal. Fi^. 1. PI. XVIII. 



10th parapod. In epitocous forms, upper part of superior lobe 

 distended with eggs. Dorsal cirrus shorter than on 1st parapod. 

 Upper side of superior lobe convex, lower concave. Ventral 

 bristles stronger than dorsal. Dorsal acicle of epitocous form 

 running far out into lower part of superior lobe. J'ig. 1 and 4. 

 PL XVII. Fig. 2. PI. XVIII. 



20th parapod. Marked by dorsal extension of upper superior 

 lobe for ova which in epitocous forms bears scattered pigment 

 spots like preceding. Ventral cirrus stout. PI. XVII., fig. 2 and 

 5. PI. XVIII.. fig. 3. 



30th parapod. In epitocous forms partly transformed. Indica- 

 ted by dropping out of old bristles and appearance of new, slen- 

 der^ones PI. XVII., fig. 1. PI. XVIII., fig. 4. Marked lengthening 

 of lower part superior lobe. Ventral cirrus bearing ventral irregu- 

 larities or buddings, which in about the 40th jmrapodium develop 

 to make accessory respiratory lobes of neuropodium ; a dorsal 

 accessory cirrus split off and lower part of 40th foot bearing 

 large respiratory lobe. PI. XVIII., fig. 5. Ventral acicle accom- 

 panied by five or six of the large unmodified bristles, while dor- 

 sal acicle is attended only by the new delicate bristles. Upper 

 part of superior lobe enormously enlarged in epitocous form. 



All the parapods including first contain eggs which are shown 

 outside in Fig. 5. 



The most striking features which readily distinguish this 

 species from any other now known are: (1) Each of the first 

 twenty somites bears on its anterior half a white stripe, on its 

 posterior half a single (lighter at its most dorsal part) or a 

 double transverse band of reddish pigment. (2) The first somite 

 is wider and more elevated than preceding. (3) Paragnathi. (4) 

 Degeneration of posterior part of body. 



VI. Nereis fucata. 



The following is taken from the diagnosis made by Wiren for 

 the epitocous male N. fucata Sav. This is given instead of a 

 diagnosis of N. fucata [i inquilina for the following two reasons. 

 First, because this is so exact a description of the commensal 

 type that Wiren describes the head and appendages, paragnathi, 

 eyes and bristles of latter by reference to the epitocous male. 

 Second, because Nereis fucata has been said to occur in many re- 

 gions on account of a supposed male epitocous form Eeteronereis 

 glaucopis, Malm. Verrill reports the latter off Watch Hill, New- 



