THE BOW FIN AND ITS ALLIES 



2885 



with an outer series of large and conical teeth, internally to which are smaller ones; 

 fulcra to the fins are either wanting or of minute size; and the dorsal fin is of 

 variable, although usually of considerable length. Having the scales thin, some- 

 what ro.unded, and overlapping, the bowfin represents a genus in which there are 

 no fulcra, and the long dorsal fin occupies three-fourths the length of the body, 

 while the anal fin is short, the caudal rounded, and the throat furnished with a 

 single gular plate, followed by a number of branchiostegal rays. The single exist- 

 ing species of the genus, which attains a length of two feet, is confined to the fresh 

 waters of the United States, where it i exceedingly abundant in some of the 

 northern lakes, but remains of extinct species have been obtained, not only 

 from the Eocene rocks this country, but likewise from the upper Eocene and 

 Miocene strata of Europe. Carnivorous in its diet, preying both upon other fish 

 and also upon aquatic crustaceans and insects, the bowfin is capable of living for 

 fully an hour out of water; and when in its native haunts, especially where the 

 water is foul, comes frequently to the surface to breathe, rising to the surface, and 

 taking in large mouthfuls of air without the emission of a single bubble. When 

 near the surface, this fish often utters a bell-like note, probably due to the passage 

 of air from the air bladder. The breeding season, during which the colors of the 

 fish are more brilliant, lasts from May till the beginning of June. The bowfins 

 breed among floating islands of herbage fringing the great lakes. Here they lay 

 thousands of minute eggs on the water plants which form the base of a series of 

 tunnels, composed partly of root fibres, and partly of a moss-like growth. Of the 

 nest thus formed, the male fish takes entire charge till the fry are hatched; the 

 development of the eggs being unusually rapid. The embryos, while agreeing in 

 many respects with those of the typical ganoids, are stated to approximate in other 

 points to those of the higher bony fishes. Megalurus, from the upper Jurassic, is 

 an allied extinct genus with a short dorsal fin and fulcra; while the Jurassic 

 Eurycormus and Eiodesmus likewise belong to the same family. 

 Among several ex- 



t inct families of 



which the members 

 are mostly of Jurassic age, we may 

 notice the Pachycormidce as repre- 

 sented typically by Pachycormus, 

 in which, while the body and jaws 

 have the same form and structure 

 as in the bow fish, the notochord 



is persistent, and the ethmoid bone fused with the vomer to form a long beak; the 

 fin rays being slender and closely set, the dorsal fin short, and fulcra absent or 

 minute. Eugnathus and Caturus are well-known members of a third family 

 distinguished by the vertebrae being usually represented by incomplete rings, by the 

 large fulcra, and the short dorsal fin; the caudal fin being forked. The Pycnodonts, 

 ranging from the Lias to the Eocene, constitute another family group, in which the 

 body is either deeply fusiform or rhomboidal; the notochord has no ossification 

 around it; the cleft of the mouth is narrow; the teeth are small, nodular, and 



Extinct 



Families 



SKELETON OF AN EXTINCT AMIOID (Caturus). 



