1 62 REPORT OF NEW JERSEY STATE MUSEUM. 



upon Daphnia and other small aquatic animals. They do not vary 

 much in color, and the males appear in equal if not greater 

 numbers than the females. The large females are rather except- 

 ional, and largest of all probably i^ inches. All are spotted 

 with blackish on the back, this fading however in the preserved 

 examples. They are not so hardy as the killies though are as a 

 rule less shy. The whole school seems to move by one impulse 

 when disturbed. They prefer a muddy bottom. 



The discovery of this little fish in New Jersey is most interest- 

 ing, as it has never before been recorded so far tO' the north along 

 the Atlantic coast of the United States. The fish has been of 

 much interest to the New Jersey Agricultural College Experi- 

 ment Station as an agent in mosquito extermination. Mr. W. P. 

 Seal has recently presented a paper on the introduction of this 

 species, and Heterandria, in New Jersey waters^ during the fall 

 of 1905. They were placed in brooks flowing into the ice-pond 

 at Westville, a land-locked pond near Delanco, a mill pond be- 

 tween Merchantville and EavesborO', and land-locked waters near 

 Delair. However, as none of them seem to have thrived or been 

 seen since, the experiment was thought unsuccessful. Though Mr. 

 Seal has suggested to me that possibly the examples I have found 

 about Cape May county may be descendants, or in fact some of 

 the same introduced individuals, I do not think this altogether 

 probable. They are more likely autochthant members of the 

 fauna of the respective streams in which they were found, as this 

 region, so far as both its fauna and flora are concerned, has much 

 in common with that of lower Delaware, Maryland and Virginia. 

 Besides, the fact that they were found associated in a perfectly 

 thriving condition with other predatory species, such as sunfish, 

 would seem to- point tO' the conclusion that they were holding their 

 own, especially as some of the sunfish were quite large. Although 

 Mr. Seal has never met with Gambusia in New Jersey he pointed 

 out that it might occur in the southern part of the State, and my 

 investigations certainly seem to bear out this statement. It is 

 however, strange that it should have escaped observation until 

 after the introduction of the species within our limits. The 



^Rep. Ent. N. J. Agric. College Exp. Sta., 1906 (1907), p. 653. 



