ON THE HKII \\lok i >| it BICOLOUS \N\ELIDS. 8l 



been distributed so that three should face toward each of the 

 -ide- ot the tank; i. e., three with head- directed toward light, 

 three auay from light, and six at right angles, three facing each 

 -ide. < )n January 26 all specimens weiv attached except one, 

 which tor some reason, perhaps injury, remained tree during the 

 entire course of the experiment, hence may he disregarded. A; 

 this date the following is the record of orientation. The three 

 facing tin- light continued in that position, one of which had 

 a imied a nearly erect attitude; the other t\\o had barely cle- 

 \ati-d tin- head to a degree sufficient to allo\\ tin- gill- to clear 

 ihe lioiiom (jf the tank when expanded. Four specimen- n<>\\ 

 face tin- \\all, and all with barely sufficient up-bending to tree 

 iln- uilU Ir-.m the bottom. The laterally directed -pecimciis 

 toiitiiiued as at first, except thai one had made a distinct up- 

 Clirve, the hi-.id elevated to an angle of about .^5 degree-. 



< MI I . -lu-iiary o the record of this tank is as follo\\-: < n speci- 

 mens facing light two are cursed upward, one neaiU \ertical, 

 peihap- 70, the other about 45, while the third remain-, a- 

 beloiv. and this in spite of the fact that direct light i- inter- 

 cepted li\ a tufaceous mass bearing tubes of I'rotulu, etc. The 

 tin -pi-< iini-ns facing the wall ha\e made con-idci able char 

 >IH- had rotated through an arc of about loo d< -gn -, \\\\ tai in- 

 ihe -id< . .uid \\iih head elevated about 35 d \notlier 



ha- aU<> n>iatel to ne.irly right angles and cur\ed ujiuard 50 

 degrei The other t\\o continue unchanged. The specimen^ 

 latn.ilK di -posed continue essentially as betc.it. excepl an up- 

 curve ol from 30 to 40 degrees. Then '"id for this aquarium 



on I'ebinaix 25 is as follows: Five spe< inien- are imu la. 

 the \\all, three continue to face the light, uhilc the others con- 

 tinue e eniially as before. 



I e lolliiuing reconls of the behaxi'T of the other aiinarium, 

 \\hich ma\ be called number two, are inteiv-iing. In thi- were 

 placet 1 rigln -jiecimens, two of which ueiv -i i-| tended head down- 

 ward, and in this position they attach them-el\e- ami continued 

 f<.r nian\ \\eeks. The others were locateil \\ith heads pre- 

 dominantly touard the wall, /'. <-., away tnun source of light, 

 onl\ one lacing light. In this tank but little -ign of light rea. tion 

 was ili-iingni-hable. The specimen originalK fating the light 



