344 



The publication of these figures is rendered the more desirable 

 from the circumstance that neither the earlier nor the later of the 

 several developmental phases of the lobster, as originally sup- 

 posed, are figured and described in the accounts, previously 

 quoted, given by Professor Sars* and Mr. S. J. Smith,f of the 

 European and American varieties respectively. Those inter- 

 mediate larval conditions that formed the subject of the above- 

 named authorities' observations are represented, in point of fact, 

 by Figures 3, 4, and 5 alone of the accompanying plate. Neither 

 the first condition in which the lobster leaves the egg, as shown 

 at Fig. i, nor the final one in which the external branchlets of the 

 thoracic limbs have become obliterated, the long antennae de- 

 veloped, and the little creature in other respects so modified as to 

 resemble the parent as represented by Fig. 5, are included in the 

 accounts here cited. The material upon which the observations 

 concerning the developmental phases of the lobster, made by 

 Professor Sars and S. J. Smith, were based, was derived, more- 

 over, from surface skimmings in the open sea, or from store 

 ponds in which adult lobsters were kept, and not from examples 

 cultivated by hand through every successive stage, as was the 

 case with those here figured. 



As shown in the accompanying plate, no less than five distinct 

 phases intervene after leaving the egg, before the little crustacean 

 becomes recognizable as a veritable lobster. In the first of these 

 (Fig. i), which is of but very brief duration, the limbs and tail 

 are applied close to the body. The beak or rostrum, which 

 forms so conspicuous a feature in all the succeeding phases, 

 appears at first sight to be altogether wanting, but is found, on 

 closer examination, to be present underneath the transparent 

 outer membrane, but tucked away out of sight between the legs, 

 after the manner of the proboscis in the pupa of a butterfly. 

 This primary larval, or "Zoea" phase, not noticed by Sars or 



* Om Hummerens postembryonale Udvikling. Af G. O. Sars, 

 Forhandlinger i Videnskabs-Selskabet i Christianana aar 1874. 



t * The Metamorphoses of the Lobster and other Crustacea.' By 

 S. J. Smith, U.S. Fish Commission Report, 1871-72. 



