S. I. /Smith — Early Stages of the American Lobster. 265 



The subsequent development of tlie embryo within the egg was not 

 observed. 



The following observations on the young larvje, after they have 

 left the eggs, have been made upon specimens obtained in Vineyard 

 Sound, or the adjacent waters, during July. These specimens were 

 mostly taken at the surface in the day-time, either with the towing or 

 hand net, and represent three quite different stages in the true larval 

 condition, besides a later stage approaching closely the adnlt : (1) a 

 free-swimming schizopodal form with the full number of cephalothor- 

 acic appendages, the abdomen without appendages, and the six pos- 

 terior pairs of cephalothoracic a[)pendages pediform and their exopo- 

 dal branches developed into powerful swimming organs; (2) a simi- 

 lar form in which the rudimentary appendages have appeared upon 

 the second to the fifth segments of the abdomen ; and (3) a form in 

 which the exopodal branches of the six posterior pairs of cephalo- 

 thoracic appendages have decreased much in size, proportionally with 

 the rest of the animal, and in which well formed appendages have ap- 

 peared npon the penultimate segment of the abdomen in addition to 

 those upon the second to the fifth segments. For convenience, I have 

 designated these forms as the first, second, and third larval stages. 

 In the next form observed the animal lias lost all its schizopodal char- 

 acters and assumed the more important features of the adult, although 

 still retaining the free-swimming habit of the true larval forms. This 

 stage I have indicated as the earliest stage of the adult form. The 

 exact age of the larvae in the first stage was not ascertained, but 

 was probably only a few days, and they had most likely molted only 

 once after leaving the eggs. 



First larval stage. 



In this stage the young are free-swimming schizopods about a third 

 of an inch (7-8 to 8-0"""-) in length (plate XIV, figs. A, B). The 

 earapax is short and bi-oad, somewhat gibbous posteriorly as seen 

 from above, and projects in front into an unarmed, long, very slender 

 and acute rostrum, whic-li is horizontal, flattened vertically, and only 

 a little less than half as long as the entire carajjax including the 

 rosti-um. The inferior angle of the anterior margin projects, beneath 

 the eye, into an acute, spiniform and prominent tooth. The cervical 

 suture is faintly indicated, but no other areolation is perceptible. The 

 posterior portions of the branchial regions are expanded laterally and 

 the posterior margin incloses a space considerably larger than the 

 base of the abdomen. 



Trans. Connecticut Acad., Vol. II. 29 July, 1873, 



