244 General Notes. [March, 



consist of flat, colorless epithelial cells, with processes by means of 

 which the cells are connected together ; the mesoderm is formed 

 by a mass of layers of oval, yellow cells. 



Color Sense in Crustacea. — M. Paul Bert has made some 

 interesting experiments on a small fresh water crustacean belong- 

 ing to the genus Daphnia, from which he concludes that they 

 perceive all the colors known to us, being, however, specially 

 sensitive to the yellow and green, and that their limits of vision 

 are the same as ours ; but Sir John Lubbock, says the Journal of 

 the Royal Microscopical Society, as the results of his own exper- 

 iments with Daphnia under different parts of the spectrum, con- 

 siders that the limits of vision of Daphnia do not, at the violet 

 end of the spectrum, coincide with ours, but that, like the ant, it 

 is affected by the ultra-violet rays. 



Hairs of the Anterior Antenna of Crustacea.— S. Jour- 

 dain. after a few words on the auditory hairs of this group, pro- 

 ceeds to point out the arrangement and structure of the processes 

 found on these antennules, which were regarded by Leydig as 

 having an olfactory function. Before describing the arrangements 

 which obtain in the representatives of different orders, he says that 

 in all cases we find a very delicate chitinous sheath, which is 

 penetrated by an offshoot from the hypodermic layer, and which 

 at its base is found to be in relation with a branch of the antennary 

 nerve ; the free end is truncated and carries a hyaline body, which 

 appears to be comparable to the rods found at the sensory ends 

 of sensory organs. These may be known as the "poils a baton- 

 net." The hairs are cylindrical in some cases, and then the chiti- 

 nous cylindrical sheath is made up of a number of joints; the 

 basal ones have thicker walls and are shorter than those which 

 are more distal. In other cases the hairs are stipitate, and then 

 the joints are ordinarily reduced to three, and the basal one, which 

 is of some length, is constricted in its middle. A detailed study 

 shows that the former arrangement is confined to the Podoph- 

 thalmate Crustacea; the hairs are found in the' young, though in 

 less number than in the adult; and, similarly, they are more 

 numerous in the higher than in the lower forms. Although there 

 seems to be no doubt that these organs respond to stimuli which 

 are something else than tactile, we are not yet in a position to 

 definitely assert that they have an olfactory function. The author 

 concludes by remarking that the characters of these parts have a 

 value for the systematist— Journal of the Royal Microscopical 



Bvthinia tentaculata. — My friend, Mr. Henry Prime, has just 

 called my attention to'an error in The Naturalist for Septem- 

 ber, i88[ (p. 716), in introduced species of shells. Instead of 

 W. H. Ballou, it should have been VV. M. Beauchamp, as in the 

 notice to which reference was made. 



