ORDER DECAPODA — CRANGON. 25 



The apparent disappearance and reappearance of lobsters in the neighborhood of New-York, 

 and in other locahties, which has given rise to many popular fallacies, may be explained by 

 considering the following facts. They naturally diminish rapidly when taken in such vast 

 numbers as we have known them to be, especially when near to a large market. When the 

 fishing ground is apparently exhausted, they are declared to have disappeared. In the mean 

 time they are undisturbed, and allowed to increase, recourse being had to other fishing grounds ; 

 and many females, with the impregnated ova, are brought to market, and kept in cars for a 

 longer or shorter period: the young are excluded, and in this way various broods are produced. 

 Many of these are caught at the docks in the vicinity of the markets, but the greater number 

 go on increasing until the word is given that lobsters are again to be found in our waters. 



The geographical range of the Lobster does not extend much farther south than the coast 

 of New-York, and ascends to the extremest north. It is taken in comparatively small quan- 

 tities on the coast of New-Jersey ; but I learn from my valued and learned friend Dr. Pick- 

 ering, that two years after building the Breakwater in Delaware bay, lobsters made their ap- 

 pearance there in great quantities. I know of no other instance where their range has been 

 extended, except by Gen. Pinckney, now deceased, who, about thirty years since, caused a car 

 full of lobsters to be emptied into the harbor of Charleston, S. C. A few of the survivors, 

 or their descendants, were captured about ten years since, but, as I am informed, they were 

 the last. 



GENUS CRANGON. Fabricius. 



Anterior feet monodactyle, and furnished with a spurious finger ; second and third pairs very 

 slender, simple ; fourth and fifth more robust. Antennae inserted in nearly the same hori- 

 zontal line ; exterior ones long, setaceous, with a large scale at the base ; intermediate ones 

 short, bifid. Gills seven in number on each side of the thorax. 



Obs. This genus, established by Fabricius, comprises about six species chiefly from the 

 polar seas. The C. vidgaris is the true Shrimp of Europe, with which our species is closely 

 allied, and by some writers considered identical. 



Crangon SEPTEMSPINOSUS. 



PLATE Vni. FIG. 24. 



Vrangim septemspinosus. Say, Jour. Acad. N:it. Sc. Vol. 1, p. 246. 



C. id.? Milne-Edwarcs, Hist. Nat. lies Crustaces, Vol. 2. p. 342. 



C vulgaria. . GouLiD, Inveileljrata of Mass. p. 331. 



Description. Body with seven spines ; one on the thorax, and one on each side in the same 

 line ; one at the external canthus of each eye, and one beneath on each side. Rostrum not 

 extending to the eyes, obtuse, with elevated margins which form a furrow on each side ex- 



Fauna — Part 6*. 4 



