SPECIMENS IN THE DEEP SEA 19 
natural rank by including the forms which, as Mr. Miers 
observes, ‘ evince the greatest degree of degradation from 
the Brachyuran type.’ It approaches in fact the group 
which till recently held a distinct position under the name 
of the Anomura. Of these Dr. Henderson observes that 
they occupy an intermediate position between the Macrura 
and the Brachyura, in regard to the limit of depth at 
which they are found, the more highly specialised forms 
being, like the Brachyura, found in shallow water and at 
moderate depths, whereas the more primitive macruran 
types extend to the abysses of the ocean. The single and 
singular specimen on which the species T'ylaspis anomala, 
Henderson (see Plate VII.), was established, ‘came from 
the greatest depth at which any anomurous crustacean . 
was taken by the Challenger,’ the depth in question being 
2,379 fathoms. In the Macruratwo genera, Benthesicymus 
and Gennidus, instituted by the late Mr. Spence Bate, 
descend to 3,050 fathoms, and have nowhere been found 
dwelling with less than 300 fathoms of water above them. 
It is not perhaps surprising that most of the specimens 
were brought up ‘in a soft, pulpy, and collapsed condi- 
tion, for it is calculated that each perpendicular mile, 
that is, each 880 fathoms of water, exercises a pressure of 
a ton upon each square inch of an animal’s surface. As 
long as the fluids within correspond with those outside the 
body, there is a state of comfort and efficiency, but when 
this equilibrium is suddenly destroyed, uot only a crus- 
tacean but any other creature is likely to feel weak and 
discomposed. 
Of the Schizopoda Boreomysis obtusata, Sars, was taken 
from a depth of 2,740 fathoms. On the other hand the 
Stomatopoda are content with far less profound explora- 
tions. Mr. W. K. Brooks reports that ‘they are usually 
found in very shallow water, and with the exception of the 
specimen of Squilla leptosquilla, taken in the trawl by the 
Challenger in the Celebes Seas from a depth of 115 fathoms, 
and a specimen of Lysiosquilla armata, which Mr.8. I. Smith 
found in the stomach of a Lopholatilus from 120 fathoms, 
they are all from very moderate depths.’ The Challenger 
