ZOOLOGY. 419 



Dimorphism. 



There are several cases of dimorphism known among grass- 

 hoppers viz., two sets of individuals in the same species, 

 which have been, or are liable to be, mistaken for different 

 species. In the species allied to the common Rocky Moun- 

 tain locust and the Eastern red-legged locust, Mr. Scudder 

 states that there are ten or twelve species of these locusts, 

 mostly occurring in the Mississippi valley, in which there 

 are two sets of individuals one with short and the other 

 with lono; winos. In one instance three varieties occur, 

 which are with little doubt to be referred to one species. 

 The dimorphic forms of any one species are found at the 

 same stations and cannot be considered racial. 



Protection, Resemblance, and Coloration. 



In an elaborate paper on the coloring matters of various 

 marine animals, Mr. Moseley, late naturalist of the Challenger 

 Exploring Expedition, calls attention to the coloring matters 

 of deep-sea animals. Very little, if any, light, he says, can 

 penetrate from the surface of the sea to depths such as 1000 

 or 2000 fathoms, and he believes that experiment has shown 

 that little or no effect is produced on sensitized paper at the 

 moderate depth of 60 fathoms. It is probably, as far as so- 

 lar light is concerned, absolutely dark at depths of 1000 fath- 

 oms and upwards, and the fact that two blind decapod Crus- 

 tacea occurred in from 450 to 490 fathoms seems to indicate 

 a condition of extreme darkness at much less depths. Nev- 

 ertheless, other animals living in very deep water have enor- 

 mously enlarged eyes, and hence some light must exist. Pro- 

 fessor Wyville Thomson and Dr. Carpenter have suggested 

 that phosphorescent animals form the source of light in the 

 deep sea. Mr. Moseley adopts this view, w T hich seems to us, 

 however, to be far-fetched, and adds that "the deep sea must 

 be lighted here and there by greater or smaller patches of lu- 

 minous Aleyonarians, with Avide intervals, probably, of total 

 darkness intervening. Very possibly the animals with eyes 

 congregate around these sources of light." "No doubt," 

 says Mr. Moseley, "in many cases the coloring of the deep- 

 sea animals, as in the case of the purple Holothurian, is use- 

 less and only an example of persistence. The madder color- 



