The Apodes, or Eel-like Fishes 141 



spicuous. The number of vertebrae is unusually large. The 

 order contains the single family Monopterida, the rice-field eels, 

 one species, Mono pier us albus, being excessively common in 

 pools and ditches from China and southern Japan to India. 



The eels of the suborder Holostomi (oAo?, complete; crro^oe, 

 mouth) differ from these mainly in the separation of the shoulder- 

 girdle from the skull, a step in the direction of the true eels. 

 The Symbranchidce are very close to the Monopterida in external 

 appearance, small, dusky, eel-like inhabitants of sluggish ponds 

 and rivers of tropical America and the East Indies. The gill- 

 openings are confluent under the throat. Symbranchus mar- 

 moratus ranges northward as far as Vera Cruz, having much the 

 habit of the rice-field eel of Japan and China The Amphip- 

 noid<2, with peculiar respiratory structures, abound in India. 

 Amphipnous cuchia, according to Giinther, has but three gill- 

 arches, with rudimentary lamina and very narrow slits. To 

 supplement this insufficient branchial apparatus, a lung-like 

 sac is developed on each side of the body behind the head, open- 

 ing between the hyoid and the first branchial arch. The inte- 

 rior of the sac is abundantly provided with blood-vessels, the 

 arterial coming from the branchial arch, whilst those issuing 

 from it unite to form the aorta. Amphipnous has rudimentary 

 scales. The other Holostomi and Ichthyocephali are naked and 

 all lack the pectoral fin. 



The ChilobranchidcB are small sea-fishes from Australia, with 

 the tail longer than the rest of the body, instead of much shorter 

 as in the others. 



No forms allied to Symbranchus or Monopterus are recorded 

 as fossils. 



Order Apodes, or True Eels. --In this group the shoulder- 

 girdle is free from the skull, and the bones of the jaws are reduced 

 in number, through coalescence of the parts. 



Three well-marked suborders may be recognized, groups per- 

 haps worthy of still higher rank: Archencheli, Enchelycephali, 

 and Colocephali. 



Suborder Archencheli. The Archencheli, now entirely extinct, 

 are apparently the parents of the eels, having, however, certain 

 traits characteristic of the Isospondyli. They retain the sepa- 

 rate caudal fin, with the ordinary hypural plate, and Professor 



