IV. The Development of Limtjlus Polyphemus. By A. S. Packard, Jr., M.D. 



Read November 16, 1870.1 



X HE earliest information we have regarding the early history of the King Crab, is a 

 note by Milne Edwards," who examined the "eggs of Limulus containing the yonng ready 

 to hatch, and found that in this stage of their development, they offered in the anterior 

 portion of their body a mode of structure but little different from that which exists in the 

 adult, while the abdominal portion of the body carries but three pairs of appendages, and 

 the long styliform tail, so remarkable in the adult, does not yet exist ; the form of the 

 abdominal portion is equally different at this period." 



The next observations wei-e made in the years 1869 and 1870, by Rev. Samuel Lockwood, 

 Ph.D., and communicated by him to the "American Naturalist" (iv, p. 257, 1870). 

 The more important facts discovered by him are incorporated in this paper. Mr. Lockwood 

 was unable to make microscopic observations on the egg, and kindly forwarded me from 

 Raritan Bay, New Jersey, where the animal is more abundant than in New England, nu- 

 merous specimens of the freshly laid eggs, in the springs of 1870 and 1871 ; and it is to 

 his ardor and enthusiasm in searching out the " nests " of the King Crab at the favorable 

 moment, by no means an easy task, that we are indebted for the means of obtaining a quite 

 complete history of the extraordinary mode of development of this interesting crustacean. 



I should also say that it was owing to the earnest solicitation of my friend, Dr. Anton 

 Dohrn of Jena, that I was first impelled to seek for the eggs of this crustacean, and send 

 him a series for study. His results, published in the "Jenaische Zeitschrift, 1871," had 

 not reached me at the time of going to press with this article. 



Previous to Mr. Lockwood's discovery of the larva of Limulus, Mr. Alexander Agassiz 

 had, as he informs me, captured with a net the larva of this species swimming fi-ee on the 

 surface of the ocean, three miles from the shore of Naushon Island, Buzzard's Bay, and 

 made a drawing of the specimen, but did not mention the fact in print. 



The eggs were laid on the 16th of May. Mr. Lockwood states that the female "spawns 

 at or near the new and full moon, in the months of May, June and July, embracing the 

 time of the extra high tides, which depend so greatly on the lunar influence. They come 

 up at a great high tide, advancing on the bottom until they reach a suitable spot near to, 

 but within, the extreme line of this great tide. Three definite advantages are in this way 

 secured. First, the spawning is performed under water, or without undue exposure ; 

 second, the line of the average high tide is thus selected ; and third, a short exposure to 



* Since this paper was offered for publication, I have been Soc. PLilomatique Extr. Proe. verb. 1838, p. 125-12G — I'ln- 



able, through a delay in the printing, to mal^e during the stitut, vi. no. 258, 1838, p. 397. I have not been able to 



summer of 1871 a new series of observations, so that this see these journals, and take the above account from J. Van der 



article has been materially changed since it was originally Hoeven's "Recherches sur I'Histoire Naturelle et I'Anatomie 



prepared for publication. des Limules.'' Leyde, 1838. 



''Recherches relatives an developpement des Limules in 



