342 Bulletin 47, United States National Museum. 



The species are few, but highly diversified in structure, constituting two 

 suborders and four families. They are probably related to the Apodes, but 

 this is not certain, and in the structure of the head they approach more 

 nearly to the true fishes, they represent degraded rather than primitive 

 types, and the line of their descent is as yet unknown. It is not even 

 certain that the forms grouped in this order are closely related. Cope 

 makes two orders of them, Ichthyocephali, (Monopteridce), and Holostomi, 

 (AmpMpnoidce of Gill, and fiymbranchidcc) . But Dr. Gill has shown that the 

 SymbranchidcB belong rather with the Monopteridae. (Symbranchidce, Giin- 

 ther, Cat., vra, 12-18, 1870.) (f<5v, together; fipayxta, gills.) 



ANALYSIS OF FAMILIES OF SYMBRANCHIA. 



a. Symplectic present. 



b. Shoulder girdle connected to the skull by a bony post-temporal ; vent behind the mid- 

 dle of the body ; vertebrae about 80 + 55 ; gills well developed ; palatine teeth in a 

 band ; gills without peculiar modification. SYMBRANCHID^, XLI. 



Family XLI. SYM BRANCHIAE. 



(THE SYMBRANCHOID EELS.) 



Body eel-shaped, naked, the abdomen very long, longer than the tail; 

 shoulder girdle attached to the skull by a well-developed, bifurcate post- 

 temporal ; snout short ; eyes small, anterior ; teeth small ; palatine teeth 

 in a band; gills well developed ; gill openings confluent in a narrow slit; 

 4 gill arches; no accessory breathing sac ; gill membranes free from the 

 isthmus. Fresh water fishes, 1 genus and 3 species known. (Symbran- 

 chidce, gennst Symbranchus, Gunther, Cat., vm, 15-17, 1870.) 



148 SYMBRANCHUS, Bloch. 



Symbranchm, BLOCH, Ichthyologia, ix, 87, 1795, (marmoratm~). 

 Unibrancliaperiura, LACEPEDE, Hist. Nat. Poiss., V, 658, 1803, (marmoratus). 

 Ophisternon, MCCLELLAND, Calcutta Journ. Nat. Hist., v, 197, 1845, (bengalensw). 

 Tetrabranchus, BLEEKEB, Nat. Tyds. Ned. Ind., u, 69, 1862, (microphthalmus). 



Characters of the genus included above. Three species known, two 

 from India, and the following, (f vv, together ; ppdyx, gill.) 



572. SYMBRANCHUS MARMORATUS, Bloch. 



Snout short, rounded or pointed ; eyes small, rather close to the end of 

 the snout. Gill opening narrow, not extending to the edge of the ventral 

 surface, generally transverse, arched, frequently appearing as a longitu- 

 dinal slit unless drawn out. Vertebrae 79 -f- 57. Color brownish, variously 

 marbled, sometimes immaculate. Tropical America, in streams from the 

 Amazon northward to southern Mexico and St. Lucia ; generally abundant. 

 Recorded northward from Vera Cruz, Trinidad, St. Lucia, Lake Peten, 

 Huamuchal, Rio Chisoy, etc. 



SymbranchuK marmorafm, BLOCH, Ichthyologia, ix, 87, pi. 418, 1795 ; GtfNTHER, Cat., vni, 15, 1870. 

 Symbranchus immaculatus, BLOCH, 1. c. , pi. 419, fig. I. 



Synbranchus transversalis, BLOCH & SCHNEIDER, 524, 1801, Guinea, after Gronow. 

 Unibranchapertura grisea, marmorata, immaculata, and lineata, LACEPEDE, Hist. Nat. Pass., v, 658, 



1)803, Surinam. 

 Synbranthus fuliginosus, RANZANI, Nov. Comm. Ac. Sci. Inst. Bonon., iv, 75, plate 11, fig. 1, 



1840, Brazil. 



Mursena lumbricus, GRONOW, Catalogue Fishes, 18, 1854, Sea of Guinea. 

 Symbranchus vittatus, CASTELNAU, An. Amer. Sud., 84, pi. 44, fig. 3, 1855, Rio de Janeiro. 



