138 The American Naturalist. [February, 
and Trematis, in Amer. Geol. for June; and in the same journal for 
April, Preliminary Description of New Lower Silurian Sponges. 
Warren Upham mentions some Marine Shells and Fragments of 
Shells in the Till near Boston, in American Journal of Science, 
May number. 
AUTOTOMY IN THE CRAB. 
BY E. A. ANDREWS. 
Te crabs when roughly handled may throw off one or 
more legs at a point close to the body, is a fact well-known 
and often observed. ; 
As little bleeding takes place in such cases, and as the crab 
may thus escape complete destruction, and is able to grow new 
legs, this power of self-amputation is of evident advantage to the 
species, and might at first sight be regarded as an intelligent act 
consciously performed by the crab under certain circumstances. 
The experimental work of Léon Fredericq has, however, 
demonstrated that such amputations are merely reflex acts 
brought about by special mechanisms, and may be included with 
similar phenomena in other animals under the term “ Autotomy.” 
From the various publications upon this subject we may ab- 
stract the chief facts relating to the crab, as given by the above 
author in his Travaux du Laboratoire, I.-II., 1887-8. 
He there shows that this rupture of the limbs is not due to 
fragility, since the weight necessary to break off a limb is many 
times that of the crab’s body, and the rupture thus produced is 
an irregular one, taking place generally at some joint of the limb, 
and not at the normal “ plane of rupture.” 
That, moreover, this autotomy is not a voluntary act was 
shown as follows: A crab when fastened by one or more legs 
endeavors to escape, but does not hit upon the expedient of 
throwing off a fastened leg, though if even a free leg is seriously 
injured, the crab then amputates it. When the brain (supra- 
