142 



VERTEBRATE ZOOLOGY 



Pikes and Killifishes (Haplomi). The Pikes (Esocidse) are well- 

 known fresh-water fishes with long body and large mouth. The 

 finest of the Pikes is the Muskalunge (Esox masquinongy) , the 

 largest of our inland game fishes. It reaches a length of six feet and 

 a weight of as high as eighty pounds; but the fisherman that gets a 

 good strike from a twenty-five pounder has about as much as he 

 can handle. 



Fundulus heteroditus (Fig. 79), the common Killifish or Mud- 

 minnow, is perhaps worthy of special mention on account of its 



B 



FIG. 79. Fundulus heteroditus , the Killifish. A, female, B, male; showing 

 sexual dimorphism in fins, and in markings. (From Newman.) 



important contribution to experimental biology. The eggs of this 

 species have furnished more material for investigation than those of 

 any other fish. If the literature on F. heieroclitus were collated it 

 would constitute many large volumes. The family (Cyprinodon- 

 tidce or Pceciliidce) to which Fundulus belongs, contains several vivip- 

 arous species, in which the anal fin of the male is used as an 

 intromittent organ for introducing sperm into the oviducts of the 

 female. 



The Heteromi. This comparatively small order of degenerate or 

 senescent fishes may be passed over with little comment. Most of 



