THANSACTIONS OF SECTION D. 757 



Thus it would seem that each province has its own peculiar form, or what we 

 call genus. All these bear a general resemblance to one another, as if they all 

 came — the northern form from its common parent, the southern from its common 

 parent, and both from one still older iu the remote history in the life of these species. 



The genus of long-legged prawns, to which Professor A. Milne-Edwards has 

 given the name of Nematocarcimis, is essentially pelagic. The several species pass 

 their lives floating in mid-water, with perhaps an occasional contact with the sea 

 bottom. 



Their geographical range is very extended, and their average floating area is 

 about half a mile below the surface of the ocean. 



The deepest point at which specimens have been taken is off the north-western 

 coast of the Celebes Islands, at 2,150 fathoms, a depth of about 2\ miles, but on 

 the western coast near the shore they have been taken at 255 fathoms. 



The next deepest range is south of Japan at 1,875 fathoms, and also at 560 and 

 350 fathoms respectively of the southern and western coast of Japan ; the 100 

 fathom line is very near the shore at a point where the sea bottom dips suddenly to 

 2,000 or 3,000 fathoms. Again, near the Island of Juan Fernandez, at 1,375 and 

 1,450 fathoms. It has also been taken far south, in latitude 61° south, in the 

 Indian Ocean, beyond the reach of any known land, at a depth of 1,260 fathoms. 

 Off Kermadec Island it has been taken at 600 fathoms, or about three-quarters of 

 a mile, also near the Fiji group. 



The very varied recorded depths, differing as they do from \ to 85 miles, is sug- 

 gestive that the animals do not reside at the extremest recorded, but that they 

 were here entangled in colonies, swimming in mid-water, and brought to the 

 surface. 



Two of the deepest recorded stations are not distant from two or three of the 

 shallowest. We must suppose that in the same region the species have either the 

 power of living under distinctly separate conditions of temperature and bathy- 

 metrical influences, or that they live suspended in the ocean over these greater 

 depths. 



According to the observations brought home, the several species vary in form 

 in points of little importance from each other, such as a longer and shorter 

 rostrum, a short or a long foot. They extend over an area that reaches from the 

 Antarctic snow line to the latitude of Japan, from the western coast of South 

 America to the eastern shores of China. 



The lowest temperature recorded is that of T5°, and the highest 5'0°. 

 They consist of nine or ten species from seventeen localities, besides those recorded 

 from the West Indies and the Cape Verde Islands by A. Milne-Edwards. 



The fresh-water genus, Atyoidea, is remarkable for the peculiarity of its form, 

 as well as for having been found in localities so distant from one another. 



The American naturalist, Randall, has described it from specimens taken in the 

 rivers and ponds of the Hawaiian Islands, where they were also found by Dana. 

 Another, but very closely allied, species was taken by the late Dr. Stimpson in the 

 island of Tahiti, whence specimens have been brought home in the ' Challenger ' 

 collection. A third has been taken in the Mexican rivers by Saussure, and a fourth 

 has been recently added to our knowledge from the rivers of Brazil by Dr. Fritz- 

 Miiller. 



These animals have a peculiar character in the articulation of the heavy chelate 

 joint of the first two pairs of pereiopoda with the carpus, being connected at the 

 lower extreme angle only. The impinging lingers of the hand are hollowed out in 

 the fashion of a spoon, the margins of which are fringed with a thick mass of long 

 hairs ; this, when the hand is open, spread as a kind of fan, gathers and detains 

 fine mud, around which the hairs close when the hand is shut, compressing it into 

 pellets, which are passed into the mouth. 



The animal thus lives on the small organisms that exist in the mud, which it 

 collects with great rapidity. 



The male of this singular little animal is not provided with any offensive 

 weapon, and is smaller than the female. 



The question naturally arises as to how far asunder can animals, that are 



