240 On Insects inhabiting Salt Water. 



mention or figure them) absence of ca mandibular beak. The 

 palpi are half as long as the fore legs. 



The present species was dredged by Prof. Verrill in 20 fa- 

 thoms, on Clark's Ledge, in Eastport Harbour. It was found 

 (four or five specimens, young and adult) " on Hydroids " &c. 

 It will be an interesting point to determine whether, like the 

 other species of the genus, it also lives in the earlier or even 

 in the adult state among the gills of Lamellibranchs, and also 

 whether it lives between tide-marks, thus agreeing with the 

 distribution of CMronomus oceanicus. At any rate, we have 

 here an insect and a mite breathing by trachea3, and extract- 

 ing the oxygen from the Avater at the great depth of 120 feet, 

 and, in the case of the Dipterous larva, with no apparent va- 

 riation from specimens living at low-water mark. In this 

 connexion I might notice the fact that we have on our New- 

 England and Labrador shores several species of mites of the 

 family Trombidiidaj which run over seaweeds and live under 

 stones between tide-marks ; and I have observed similar spe- 

 cies at Beaufort, N.C., and Key West, Florida. 



As regards the distribution of the species of brine-insects, 

 several questions of interest arise. How are we to account for 

 the origin of the Ej^liydra lialophila in such prodigious quan- 

 tities in the vats of the Equality Salt-works of Illinois, a 

 locality remote from salt lakes and the ocean shores ? Are the 

 brine species of the salt lakes of Utah and California remnants 

 of an oceanic fauna and of the Tertiary period ? or are they of 

 recent and local origin? Have these brine-insects acquired 

 their singular tastes within a recent geological period (say, 

 the Quaternary), having lived at fii'st, as do their allied spe- 

 cies, in foul fresh water, or amid decaying matter in damj) 

 localities ? Before these and other questions can be answered, 

 we must have analyses of the waters, and a review of the 

 European literature of the subject*, and larger collections of 

 brine-animals from our own country. 



Peabody Academj' of Science, Salem, Nov. IG, 1870. 



* I am indebted to Mr. F. "Walker, of London, for the following^ note 

 on tlie habits of the English species of Ephydra and its allies. lie wiites 

 under d.ate of December 6, 1870 : — " I have observed species of Ephydra 

 along the sea-shore, as well as several inland aquatic species. I am in- 

 debted to my friend the late A. H. Ilaliday for the descriptions of the 

 .species of this and the nciphbouriug genera in my ' Diptera Rritannica,' 

 vol. ii. I am not aware that the species are very dilierent in tlieir habits ; 

 and he does not mention them as such. He writes of the following species 

 as occurring on the sea-shore : — 



" Ilccamcda albicans, on sandy coasts, especially on fresh rejectamenta. 



" Hydrellia thoracica, on the sea-coast. 



" Atissa pyymcva, in a salt marsh. 



" GUiumthc. ripicola, muddy sea-coast. 



" Scatella sibilant, sea-coast. 



