36 IOWA ACADEMY OF SCIENCES. 



caves has rendered both brilliant colors and large eyes useless, 

 and thus both have been rigidly suppressed. 



The presence of phosphorescence in so many animals which 

 are supposed to be sightless, e. r/., pennatulids, gorgonians and 

 hydroids, is hard to explain.* Indeed, it is not properly 

 within the scope of this paper to explain it. A suggestion 

 occurs to me, however, that may be worth noting. These 

 animals feed, for the most part, on minute Crustacea and on 

 protozoa. Most Crustacea, and more particularly their embryos, 

 have functional eyes. May they not he attracted by light, as is 

 the case with shallow- water forms? The protozoa are gener- 

 ally without distinct organs of vision, but many of them are, 

 nevertheless, apparently attracted by light. If this is true, 

 we have a reason for phosphorescence among the fixed coelen- 

 terates. It attracts the prey. This, to my mind, is more 

 plausible than the theory that it is a protective contrivance. 



We may thus imagine the bottom of the sea to be for the 

 most part dark, but with limited areas where are congregated 

 phosphorescent animals that give forth sufficient illumination 

 to render striking colors, particularly red, yellow and green, 

 distinctly visible, enabling them to play the same role that 

 they do in shallow water, and bringing them within the prov- 

 ince of the same laws. 



NOTES ON THE HEMIPTERA OF NORTHWESTERN 

 IOWA. 



BY HERBERT OSBORN. 



From the difference in geological and floral conditions of 

 the northwestern part of the state, we might naturally expect 

 a somewhat interesting insect fauna. Occasional specimens of 

 species, rare or unknown in the central part of the state, have 

 come to hand and, especially in Hemiptera, have served to 

 strengthen a desire to investigate more thoroughly the fauna 

 in this order. Many of these additions have been due to the 



* VerriU thinks that phosphorescence in these cases is of value in warning- away 

 enfmies from the nettling- ceUs. I have been unable to find neniatocysts among- the 

 gorgonidaj and have neverseen them mentioned as found among pennatulids. They 

 are seldom of large size among the hydroids. 



