488 WILLIAM K. GREGORY 



the adipose dorsal is frequently lost, the premaxillaries lengthen 

 and grow fast to the slender maxillary which is excluded from 

 the oral border (Boulenger), and an elaborate system of photo- 

 phores is developed. The group is known from numerous fossil 

 genera in the Cretaceous and Eocene. 



The Chirothricidae (Cretaceous forms) are probably related 

 to the Scopeloids, but superficially resemble Flying-fishes (Exo- 

 ccetus). The "wings," however, are formed by the greatly 

 enlarged ventral fins, which are placed very far forward. 



The Cretaceous Enchodontidae are said to agree with con- 

 temporary Isospondyls in most respects, but are progressive 

 in the backward enlargement of the delicate premaxilla, which 

 nearly excludes the maxilla from the border of the mouth. The 

 long, slender teeth are acrodont (i.e., not in sockets but fused 

 with the supporting bone). An adipose fin is often present. 

 Their nearest existing relatives are the deep-sea Alepisauridas. 



The true Haplomi as understood by Gill, Jordan, and Starks, 

 include only the Mud-minnows (Umbridae) and Pikes (Eso- 

 cidae) of Europe, Asia, and America, the Killifishes (Poeciliidae 

 or Cyprinodontidae) of Southern Europe, Africa, Asia, and 

 America, and the famous subterranean Blind-fishes (Amblyop- 

 sidae) of the southern United States. These families have 

 been grouped by E. C. Starks 1 in a recent paper on the osteology 

 of the Haplomi as follows: 



Esocidae (Pikes) 



Umbridae (Mud-minnows) 



Superfamily Esocoidea 



Order Haplomi " Poeciloidea Poeciliidae (Killifishes) 



Cyprinodontinae 

 Pceciliinae 

 ' ' Amblyopsoi- 



dea Amblyopsidse (Blind-fishes) 



"The families of the Haplomi," he says, "have either widely 

 diverged from each other or are not of the same line of descent. 

 The order is not held together by any important character, 

 though some very peculiar characters may be used to rather 

 widely separate three groups." 



1 "A Synopsis of Characters of Some Fishes belonging to the Order 

 Haplomi," Biological Bull., Vol. VII, No. 5, Oct. 1904, pp. 254-262. 



