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 Tylaspis 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 

 2,375 fathoms. In the Macrura two genera, Bentliesicj/mus 

 and Gennddas, 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, not 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 leplosquilla, 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. S. I. Smith 

 found in the stomach of a Lopholatilus from 1 20 fathoms, 

 they are all from very moderate depths.' The Challenger 



c 2 



