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ACTINOPTERYGIT. 
Suborder YI. APODES. 
Notochord more or less persistent, but the vertebral centra 
always complete constricted cylinders, none coalesced ; tail tapering, 
usually without expanded or fused neural or haemal supports at the 
extremity. Symplectic bone absent; mandible simple, each ramus 
consisting only of two elements (dentary and articulo-angular). 
Pectoral arch not suspended from cranium; precoracoid arch 
absent; infraclavicular plates absent; pectoral fin with more than 
five basals. Pelvic fins absent. Scales rudimentary or absent. 
In the living forms—air-bladder, when present, connected with the 
oesophagus by a duct in the adult (physostomous), optic nerves 
decussating, intestine without spiral valve, and reproductive organs 
without efierent ducts. 
Family MUR.^NID^E. 
Trunk much elongated, the caudal region being relatively very 
long. Parietal bones large and meeting in a median suture; 
squamosal suturally united with parietals and covering the greater 
part of the otic region. Premaxillse small and fused with the 
ethmoidal rostrum ; maxilla well-developed, forming most of the 
upper border of the mouth ; pterygo-palatine arcade much reduced 
or rudimentary. Branchial and opercular apparatus usually more 
or less reduced; generally a few delicate branchiostegal rays. 
Vertebrae very numerous, those of the abdominal region with short 
and broad transverse processes, small and delicate ribs, and very 
short neural spines. Intermuscular bones present. Fin-fulcra 
absent; fin-rays articulated and divided distally; dorsal and anal 
fins excessively extended, and a separate caudal fin almost always 
absent. 
The extinct species of this family are too imperfectly known to 
be generically determined with certainty. It is evident, however, 
that they represent some of the more generalised types; and the 
Cretaceous genus mentioned below is unique in retaining a normal 
caudal fin. 
A figure of the skeleton of Anguilla is published by Agassiz, 
Poiss. Foss. vol. V. pi. D. Some illustrations of cranial osteologj* 
are given by Storms, Bull. Soc. Beige Geol. vol. x. (1898), pi. vi. 
