INFLUENCE OF ENVIRONMENT 



251 



THE FRESH WATER KILLY (Fundidus diaphanus Le Sueur) 

 which reaches a length of about five inches, has the same range as the 

 common killifish, but shows a tendency to confine its movements to open 

 channels and currents. The young mingle and move with the common 

 killifish, but as they grow older separate more. This species differs from 

 its allies in that it has a tail squarely cut off and not rounded. The fe- 

 males are olivaceous. The sides are traversed by fifteen to twenty pearly 

 white crossbands. 



Fig. lxxviii. Common killifish. Fundulus hetoroclitus macrolepidatus Wal- 

 baum. Male. (From Jordan and Evermann, U. S. Nat. Mus., Bui. 47). 



THE RAIN WATER FISH {Lucania parvia Baird) is a very small 

 species, ranging from one and one-half to two inches in length. The 

 males are olive or pale brown, with bluish reflections ; the edges of the 

 scales are darker. The females have pale olive fins without black spots 

 or edging. In life the body is almost transparent. This species appears 

 to be confined to the south Jersey marshes. It is not an active fish nor 

 is it a top feeder. It does not overrun the marshes like the killies. 



THE SHEEPSHEAD MINNOW, otherwise known as the "varie- 

 gated minnow" and "pussy minnow^^ (Cyprinodon variegatus Lace- 

 pede) occurs ever3'^where along the Jersey coast. Like the preceding 

 species it collects in pools. Both this and the rain water fish will live in 

 ditches and pools foul with noxious gases. The general appearance of 

 the sheepshead minnow is quite sufficient to separate it from the preced- 

 ing species. 



Speaking of all this species, Mr. Seal (23) says: "Breeding, princi- 

 pally, in shallow pools left on the mud flats by the receding tides, the 

 young appear in the spring in enormous numbers and remain there 

 until they attain a considerable growth — one and one-half or two 

 inches — when they begin to run in and out with the tide. As the tide 



