270 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 2 



live for a year or more in closed vessels of sea vi^ater without special 

 feeding. Fragments from any part of the body back of the head regenerate 

 about equally well, and they may even be split longitudinally or cut into 

 small sectors, with a minute but fully organized worm resulting from 

 each piece, if not too small, which contains a portion of one of the nerve 

 cords (Coe, 1934). Fragments often encyst during the regenerative proc- 

 esses. Grafting of longitudinally split fragments is sometimes successful 

 if the polarity of the two pieces coincides. 



The species is closely similar, both morphologically and physiologi- 

 cally, but not identical with L. socialis Leidy and L. sanguineus (Rathke) 

 Mcintosh, the latter erroneously called L. ruber, slender form, by Nus- 

 baumandOxner (1910, 1911). 



Genus MIGRURA Ehrenberg 

 Eight species of this genus have been found on the Pacific coast. 



Key to Species 



1. With narrow white bands or rings encircling body at intervals 



throughout entire length 2 



1. Without conspicuous transverse bands or rings 4 



2. Tip of head red or flesh color; ventral surface white .... 3 



2. Tip of head white; both dorsal and ventral surfaces of body 

 brown or blackish, lighter ventrally wilsoni 



3. Dorsal surface deep purple or reddish brown, ventral surface 

 white ; dorsal side of head red, deep orange, or vermilion . . . verrilli 



3. Dorsal surface dusky or gray; head flesh colored . . . impressa 



4. Dorsal surface with conspicuous spots and blotches .... 5 



4. Without distinct spots, except on tip of head 6 



5. Pale yellow; dorsal surface nearly covered with black or dark 

 brown spots and dots, often somewhat elongated and arranged 

 in irregular longitudinal lines; in some individuals spotting pat- 

 tern is divided into rectangles by narrow transverse lines; 6 to 



15 ocelli in single row on each side of head pardalis 



5. Grayish after preservation (color in life unknown), thickly 

 mottled on both dorsal and ventral surfaces with coarse conflu- 

 ent brownish blotches, which often fuse together posteriorly to 

 form a continuous brownish color nebulosa 



6. Rosy, flesh color, or red ; ocelli absent 7 



