41 o The American Naturalist. [May, 
some molluscs brought from the Holy Land were placed in the 
college collection and duly labelled, when some of them 
exhibited their vitality by walking off the museum cards. 
The " Horseshoe," or King Crab which anyone who goes 
to the Atlantic seaboard can usually find on any sand- flat, 
is an animal remarkable not only for its great antiquity, 
but for its extreme hardiness which is perhaps one cause of 
its great age. They are found fossil in the primary rocks, 
in the Cambrian and Silurian formations, and therefore except- 
ing the Foraminifera, they are among the oldest animals known. 
The related trilobite has perished utterly, and a whole army of 
other forms, but the King Crab has existed during all these 
ages and has altered but little ; hence we must infer that their 
conditions of life have been nearly uniform during this immense 
period. When the embryology of this animal was being 
studied at the Marine Laboratory of the John Hopkin's Uni- 
versity at Beaufort, N. C, a few years ago, an attempt was 
made to fertilize the eggs artificially. As the ova did not at 
first show any of the usual signs of development, but began to 
swell as if undergoing decomposition, they were set aside 
and forgotten. In about 3 weeks from this time the dish was 
examined by chance, when it was seen that the young king- 
crabs were just leaving the shell, notwithstanding the fact that 
the water in which they had lived was impure, and had nearly 
evaporated. The following anecdote which illustrates what 
the adult King Crab can stand, I heard from Professor Brooks 
of the Johns Hopkins University. While he was studying with 
Louis Agassiz at Cambridge, Milne-Edwards, the renowned 
French naturalist sent to this country for some specimens of the 
American King Crab, on which he was then preparing his well 
known monograph. The animals as soon as captured were 
taken to the Cambridge laboratory and thrown under a build- 
ing, where they remained some weeks, exposed to a low 
temperature. They were then packed up and sent abroad, 
and when they reached Paris, some of them were still alive. It 
is interesting to notice that this animal is not a Crab at all, nor 
indeed a Crustacean, as the recent study of its development has 
