150 PROCEEDINGS : BOSTON SOCIETY NATURAL HISTORY. 
express my especial gratitude to Dr. H. C. Bumpus, now director of 
the American museum of natural history, for the assistance and 
guidance furnished me throughout the work at both institutions. I 
am also indebted to Dr. A. D. Mead, of Brown university, and to 
Dr. H. M. Smith, of the United States fish commission, for ample 
provision extended to me during my study. 
The Adult Crab. 
Throughout the region about Woods Hole, the genus Eupagurus 
is practically supreme and is represented there in the shallower 
waters by four species, viz .: long {carpus, annulipes , acadianus, 
which is apparently only a variety of the European bernhardus , 
and pollicaris. Of these, E. longicarpus is the only one generally 
distributed along the shore. It is extremely abundant and extends 
from tide-water to a depth of about twenty-five fathoms and is 
associated over the lower limits of its range with acadianus which 
is a deeper-water species, and in the shallow waters with pollicaris 
and annulipes , but of these only pollicaris occurs along shore and 
then only in a few localities. 
Because of its distribution and abundance, E. longicarpus was 
selected for the present research. But after much of the work had 
been completed, it was discovered that the larvae of annulipes could 
not be distinguished from those of the selected species, as their 
slightly smaller size furnished no adequate criterion for their separa¬ 
tion. Whenever the annulipes larvae were unusually abundant, 
as was shown by the occurrence of their adolescent stages in the 
experiments, I could note no difference in the ontogeny from the 
periods when undoubted longicarpus predominated. In sections 
also, the smaller specimens of any stage, presumptive annulipes , 
were wholly like their larger companions. This is perfectly in 
accord with what we know of the adults themselves. Eupagurus 
longicarpus and E. annulipes differ only in specific details. E. 
longicarpus is the larger, has slender chelipeds and its coloration is 
diffuse. E. annulipes , on the other hand, has stout chelipeds and 
prominent belts of brown pigment on the anterior thoracic limbs. 
My research is therefore not invalidated, but rather enriched by the 
confusion. It becomes a life history of two, instead of one species. 
