522 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



C— THE METAMOEPHOSES OF THE LOBSTER, AND OTHER 

 CRUSTACEA.— BY S. I. SMITH. 



Most of the larger crustaceans of our coast, whatever may be their 

 liabits when adult, are, in the early stages of their existence after hatch- 

 ing from the eggs, essentially free-swimming animals, living a large part 

 of the time near the surface of the water. In this stage they are con- 

 stantly exposed to the attacks of other predaceous animals, and, as they 

 occur in vast numbers, afford food for many valuable fishes. They are 

 most abundant at the surface in calm, clear weather, and they especially 

 resort, like the young of many other marine animals, to spots and streaks 

 of smooth water where the tidal currents meet. 



Very little has yet been written upon the forms or habits of the young 

 crustaceans of our own coast ; but, in connection with the investigations 

 carried on in Vineyard Sound and Buzzard's Bay, a great amount of 

 material for such work was collected. This material has not yet 

 been fully studied, and only a sketch of some of the more important re- 

 sults is presented in this report. During the few weeks in June and 

 July, in which I was myself at Wood's Hole, the time was so fully occu- 

 pied in collecting, that very little time was left for studying the animals 

 while alive; hence most of the observations which follow, except occa- 

 sionally those on color, have been subsequently made from specimens 

 preserved in alcohol. While at Wood's Hole, I was much assisted in 

 obtaining these young animals by every one then associated there in the 

 work of the commission; and I would especially acknowledge such 

 assistance from Dr. W. G. Farlow, Mr. V. N. Edwards, and Capt. John 

 B. Smith. After I left, the collectiug was kept up as before, and many 

 valuable notes were made by Professors Verrill and J. E. Todd. 



Si^ecial attention was given to the early stages of the lobster, as per- 

 haps the most important crustacean found on our coast, and I have gone 

 more fully into the account of its early history than that of any other 

 species. As this will serve as an example to illustrate the development 

 of most of the other Macrourans, it is presented first. 



Numerous specimens of the free-swimming young of the lobster, in 

 different stages of growth, were obtained in Vineyard Sound during 

 July, but it was too late for any observations upon the young within the 

 egg. This deficiency was partially supplied by a few observations at 

 New Haven in 1872. Eggs taken May 2, from lobsters captured at New 

 London, Connecticut, had embryos well advanced, as represented in fig. 

 4. In this stage the eggs are slightly elongated spheroids, about 2.1"^'" 

 in the longer diameter, and 1.9""" in the shorter. One side is rendered 

 very opaque dark green by the unabsorbed yolk mass, while the other 

 shows the eyes as two large black spots, and the red pigment spots on 

 the edge of the carapax, bases of the legs, &c., as irregular lines of 

 pink markings. 



In a side view of the embryo, the lower edge of the carapax (6, figure) 



