G-2 MR, W. K. BROOKS ON LUCIFER: 



stating that I have fortunately been able to complete his observations upon Lucifer, 

 and to furnish a very perfect account of its entire metamorphosis, as well as a few 

 important facts with reference to its development in the egg. 



At the end of April, 1880, I found a single specimen of Lucifer with two eggs 

 attached to one of its appendages, and I was led by the great importance and interest 

 of the subject to make every effort to trace its life-history. For four months I met 

 with no success whatever, but about the 1st of September I found a few advanced 

 larvas, and traced them to the adult, and I then succeeded in finding earlier stages 

 and tracing them as far as the stages which I had previously found, but it was not until 

 the last week of my season at the sea-shore that I succeeded in hatching the Navplius 

 from the egg, and the last gap in my series was bridged by a moult which occurred 

 only a few hours before my departure. 



As the result of my four months' efforts I can now state that I have seen the eggs 

 of Lucifer pass out of the oviduct. I have seen the Nauplius embryo escape from the 

 same egg which I had seen laid, and I have traced every moult from the Nauplius to 

 the adult in isolated specimens. There is therefore no Crustacean with the meta- 

 morphosis of which we are more thoroughly acquainted than we now are with that of 

 this extremely interesting genus. 



Not only is it true, as WiLLEMoES-SuHM has pointed out, than DANA'S Erichthina 

 demissa is a larval stage of Lucifer, but that DANA'S Sceletina armata is a later stage 

 in the same series, while some of the forms which he includes in his genus Furcilta 

 are also, in all probability, Lucifer larvre. 



The occurrence of a free Nauplius stage of development in the life-history of one of the 

 higher Crustacea is a matter of such profound significance in the scientific discussion 

 of the phenomena of embryology in general, that it can hardly be accepted without 

 question so long as there is any possibility of error. Two of the observers who have 

 testified to its occurrence have based their conclusions upon evidence which would be 

 perfectly satisfactory in any ordinary case, but as they did not actually trace all the 

 stages of development their statements do not stand the severe analysis which the 

 importance of the case demands, and certain naturalists have therefore refused to 

 give them unqualified acceptance. 



The third observation was made so many years ago, and the larva is so briefly 

 described, that it would not be safe to assume, in the absence of all corroborative 

 evidence, that it is a Nauplius at all. 



In December, 1838, DANA found in the harbour of Ptio de Janeiro great numbers of 

 specimens of a Schizopod, which he described (' United States Exploring Expedition 

 during the Years 1838-1842,' under the command of CHARLES WILKES, U.S.N., 

 vol. xiii., part i., p. G54) as Macromysis gracilis. In the brood-pouches of some of 

 his specimens he found an abundance of eggs and developing embryos, several of 

 which are shown in his plate 45, fig. 5. He made no careful study of their structure ; 

 his notice of them in the text is only a few words ; and his figures are very small, 



