1GS Mr. G. A. Boulenger on the Suborders and 



skull, through reduction or loss of either the maxillary or the 

 pterygo-palatine arches. 

 Five families : — 



Maxillaries present, separated on the median line 



by the ethmo-vomer ; palato- pterygoid 



present, connected with the hyoniandibular 



and quadrate ; gill-clefts separate, opening 



into the pharynx by wide slits ; tongue 



present ; vent far removed from the head. . 1. Anguillidee. 

 Distinguished from the preceding by the position 



of the vent, which is close to, or at no great 



distance from, the gill-openings 2. Nemichthyidee. 



Mamillaries narrowly separated on the median 



line, their extremity strongly attached by 



ligament to the mandible ; pterygo-palatine 



arch absent; gill-openings externally con- 

 fluent into a single ventral slit 3. Synaphobranchidce. 



Maxillaries narrowly separated on the median 



line, extremely elongate ; mouth enormous ; 



pterygo-palatine arch absent ; hyomandi- 

 bular arch slender and movably articulated 



to the cranium ; branchial arches far behind 



the skull 4. Saccoplwryngidce. 



Maxillaries absent, replaced by the palato- 



pterygoid, the mouth bordered by the latter 



and the ethmo-vomer ; palato-pterygoid 



bone separated from hyomandibular arch ; 



branchial openings into the pharynx narrow 



slits ; no tongue 5. Muvcenidce. 



Suborder V. II A p l m i. 



Air-bladder, if present, communicating with the digestive 

 tract by a duct. Opercle well developed. Pectoral arch 

 suspended from the skull ; no mesocoracoid arch. Fins 

 usually without, rarely with a few spines ; ventrals abdo- 

 minal, if present. Anterior vertebra3 distinct, without 

 Weberian ossicles. 



The absence of the mesocoracoid arch distinguishes the 

 Haplomi from the Malacopterygii, with which they are 

 united by various authors. They lead to the Percesoces 

 through the Cyprinodontids, and to the Lower Acantho- 

 pterygians, such as the Berycids, through the Scopelids, 

 IStephanoberycids, and Percopsids, as is evidenced by the 

 structure of the mouth and the forward position in some of 

 the genera of the ventral fins, which, however, are never 

 attached to the pectoral girdle. Most of the forms which 

 are here included inhabit either fresh waters or the deep sea. 



