THE OSTEOLOGICAL CHARACTERISTICS OF THE FAMILY SIMEN- 

 CHELYID^. 



BY 



Theodore Gill, M. D., Ph. D. 



lu 1878 several specimens of a remarkable fish, with au auguil 

 liform bodj" bat with a head very unlike that of an eel, were received 

 at the Smithsonian Institution. So different was the fish from an eel 

 that Messrs. Goode and Bean were doubtful as to its relations and re- 

 ferred it to me to determine its affinities, kindly resigning to me the 

 privilege of naming and describing it. I determined it to be the rep- 

 resentative of a peculiar family, but to be otherwise a true eel or apodal, 

 and drew up a preliminary description, which wa.s published by Messrs., 

 Goode and Bean in "a list of the fishes of Essex County, including 

 those of Massachusetts Bay," contributed to the " Bulletin of the Essex 

 Institute. " * The new type was introduced in the following terms : t 



This strange form has much of the physiognomy of a Carapus {Gymnotus), and has 

 a short, blunt snout, but is a true Apodal and has an eel-like tail. The branchial 

 apertures are short longitudinal slits on each side of the throat below the pectorals, 

 which are well developed : the dorsal commences about a head's length behind the 

 pectorals, the anal considerably in advance of the second half of the total length. 

 The skin has scales like those of Anguilla, linear, scattered, and disposed at right 

 angles to e.ach other. The head is very short ; the premaxillaries and maxillarios 

 of each side consolidated iuto a single piece} and separated from thaf of tLe 

 opposite side by the ethmoid, and provided with lamelliform posterior margin and 

 an expanded antero-termiual process; nuindible very deep; teeth blunt, uniserial ; 

 the operculum saber-shaped. The type appears to belong to the suborder of Enchi - 

 lycophali. The single species {Simenchelys parasiticus) is dark brown colored in life, 

 and individuals have been found burrowing iuto the flesh of the halibut. 



After too long au interval, I supplement the diagnosis thus given by 

 the following detailed description of the characters. 



Meanwhile the name has appeared in several catalogues and works, 

 and the family has been adopted by Messrs. Goode, Bean, and Jordan. 



In 1889 numerous examples of au anguilliform fish were taken in 



* "Sinieucbelys parasiticus Gill, MS. Pug-nosed eel. Several specimens of an 

 undescribed eel-like fish were obtained on the halibut trawls, on the off-shore banks." 

 Goode and Bean, op. cit., p. 27. 

 t Gill MSS. in op. cit., v. 11, p. 27, 1379. 



}The suggestion that each jaw bone represented au intermaxillary and supra- 

 maxillary (borrowed from Prof. Cope) was not more haj)py than previous guesses. 

 Proceedings of tlio N.itional Museum, Vol. XIII — No. 817. 



239 



