1895.] NATURAL SCIENCES OF PHILADELPHIA. 193 



southern hemisphere is given the possibility to re-ascend into the 

 litoral, and two litoral species are, in fact, found in Australia and 

 New Zealand. 



The genus Sabinea contains two northern species, one of which, S. 

 septemearinata, is a true arctic circumpolar one, the other, S. sarsi, 

 is found on both sides of the northern Atlantic. Both descend into 

 greater depths, to about 150 fathoms. The third species, S. hystrix, 

 is an abyssal one, found in 400 to nearly 900 fathoms, and its range 

 extends more southward, from the eastern coast of United States to 

 Guadeloupe in the West Indies. 



The two known species of the most extreme genus of the second 

 branch of Crangonidre, Paracrangon, live on the western coasts of 

 America, probably in greater depths; at least P. areolatus is recorded 

 from over 600 fathoms. 



The last genus, Prionocrangon, is very peculiar and its affinities 

 are not certainly known. It probably is allied to Pontophilus, and 

 then its habitat, in the deep sea of the Indian ocean, 200-400 

 fathoms, would not be strange, since Pontophilus contains also 

 tropical species living in deeper water. 



The distribution of Crangonidce may be thus summarized: 

 The "regions of life" 13 in which Crangonidse are found, are the 

 litoral and the abyssal. Regarding the "fades," 14 the Crangoniclre 

 are principally, as we know, benthonic 15 in sand and mud. These 

 habits admit a universal distribution of the family, but the genera 

 and species are more restricted. 



The litoral species especially are not cosmopolitan, but are con- 

 fined by barriers. Except the tropical genus Pontocaris,, which 

 must be regarded as a survival, the litoral Crangonidse are almost 

 exclusively limited to the northern hemisphere, and the seas of 

 tropical temperature must be considered as the climatic barrier pre- 

 venting the distribution of Crangonidie southward. Only a few 

 species are adapted to the warmer seas, especially Crangon catapkractus 

 in Senegambia and Pontophilus carinicauda in China, Generally, 

 the Crangonida3, originating in the cooler northern hemisphere, were 



13 "Lebensbezirke," J. Walther, Bionomie des Meeres, 1893, p. 13-15, p. 87- 

 176. — Walther does not give a satisfactory and correct definition of* this word, on 

 account of wbicb his detailed discussion concerning this term is wholly out of 

 place. Notwithstanding, the idea of '" regions of life " is a very good one. 



14 Walther, ibid. p. 25-34. 



15 See Haeckel, Planktonstudien, 1890, p. 18ff. 



