THE NAUTILUS. 35 



No temperatures were taken, for on the face of it the temperature 

 was uot tlie controlling factor at that time and place, the same forms 

 and spawn occurring indifferently in shallow, sun-warmed pools 

 pleasant to the hands, and in deep, unsunned crevices at extreme 

 low tide when one's breath condensed in clouds over the numbing 

 water. This is not to say that temperature may not be the control- 

 ling factor in the initiation of the migration impulse or even in the 

 actual deposition of spawn, which latter may perhaps always take 

 place at high water when the temperature conditions of the pools 

 would be equalized. 



The section worked at Rocky Neck did not exceed 300 yards in 

 length, and at Brace's Cove about 200. Three days were given to 

 the former and one to the latter. Every day-light tide was worked 

 industriously, and attention was wholly concentrated on nudibranchs. 



The " census" was as follows: 



Coryphella rufibranckialis manavensis (Stimps.),^ typical, 43 speci- 

 mens collected and about 30 more seen — total, say 75. All but 6 at 

 Rocky Neck. All well-grown, if not fully adult, except three or 

 four apparently about half-gi-own. 



Coryphella riijibranchialis chocolata var. nov. Externally not 

 separable by me from the foregoing except by the color of the cores 

 of the cerata and of the body, which is a true chocolate-brown, dark 

 for the cerata, light for the body, as contrasted with the varied reds 

 (varying from pink to ginger, salmon and scarlet) of the typical form. 

 The dentition and internal anatomy have not yet been examined, 

 but as there is undoubtedly intergrading in the color, no very dis- 

 tinctive character should be anticipated. I have seen this form 

 before, but never more than one or two specimens at a time. As a 

 mere color variety (and for all we actually know, a mere physiological 

 phase) it may be thought not worth a name. At the same time the 

 intergrades are few and the series incomplete; and the chocolate 

 forms, in life, occurred markedly segregated from the others. It is 

 at least possible to point out a tangible character by which it differs 

 from typical mananensis, which no one has yet done for the differen- 

 tiation of mananetisis from rvfibrancMalis. Should mavanensis prove 



' So called by me for the present in the provisional belief that Stimpson's 

 form — if separable at all, which I doubt— is only a variety of the European 

 form. Our knowledge, and consequently the nomenclature, of the group of 

 red-gilled Eolids on this coast is in deplorable condition. 



