26G W. J. CROZIEK AND LESLIE B. AREY 



the fact that slime glands are important for the production of a 

 slippery condition of the whole surface of the animal; and that 

 repugnatorial glands, in part at least under nervous control 

 (Crozier, '16 b; '17 a), are also involved in the creature's effector 

 equipment. In addition to ciliary activity and several types of 

 gland secretion, muscular movements of some variety are evi- 

 denced. Chromodoris has no hard supporting skeleton; its 

 movements depend conspicuously upon the distribution, under 

 muscular pressure, of the body fluids, and comprise: bending 

 movements, twistings, contraction and extension of the whole 

 body, and of its projecting outgrowths — tentacles, 'rhinophores,' 

 and gills; protrusion and retraction of the proboscis, of the 

 genital papilla, and of the oviduct; rhythmic contractions of the 

 extended oviduct during egg laying, as well as local contractions 

 of practically every part of the animal's surface. 



C. zebra is functionally hermaphroditic, and reproduces at all 

 times of the year (Smallwood, '10; Crozier, '17 b). The ani- 

 mals employed in this work were for the most part collected in 

 Fairyland Creek, near the laboratory of the Bermuda Biological 

 Station, where a practically unlimited supply of material was 

 available during spring and early summer, when these experi- 

 ments were chiefly performed. This nudibranch is easily main- 

 tained in aquaria (Crozier, '18 d), contrary to Smallwood's ('10) 

 belief, but freshly collected individuals were almost always used. 

 The largest specimens collected in late spring are the least viable ; 

 at a length of 16 to 18 cm. Chromodoris zebra undergoes natural 

 death. It would be of interest to determine the growth rate of 

 the animal, but this cannot as yet be attempted. A more de- 

 tailed account of the natural history of C. zebra will be found 

 in reports dealing with the phenomena of its breeding habits 

 (Crozier, '17 d, '18 d) and of the coloration of the species (in 

 course of publication; Crozier, '16 b). 



