GYMNOTID.K. 125 



in their order, and the Gi/niiiotidtr and Leptocephalida in their 

 under orders, be considered as families of the lowest organisation. 



The Gijmjtotichc form an interesting family in the order [Physo- 

 siOHfi), of which the Salmonidfc fomn the highest family, and the 

 dorsal thong {peitclw) of the genus Stcrnnrchus can be compared 

 only with the adipose fin of the Sal monoids. 



The first doubt of the Gi/mnotidce belonging to the Apodals was 

 raised by Professor Reinhardt in his excellent treatise on the swim- 

 bladder of the Gi/iniiotini, in the Archiven for 1854 (p. IHO), wherein 

 he remarks that they are without doubt connected by certain abdo- 

 minal families to the order of Plujsosto)iii, namely, by the Characini. 



In the present work I have profited by the able treatise on the 

 Gymnotida by Johannes Muller and Ti'oschel in the Flone Ichthyo- 

 loyicce, by Reinhardt's dissertation on the swim-bladder of the 

 Gymnotini, by DOrbigny's voyage {Poissous), edited by Professor 

 Valenciennes, and by the voyage of the Bonite. The voyage of 

 Castelneau has made known to me four new species, which as yet I 

 have not met with in nature so as to compare them with his de- 

 scriptions, and the rivers in which these four species were taken 

 are not mentioned. 



I have to return many thanks to Professors Dumeril and Lichten- 

 stein, for the use of the materials existing in the Paris and Berlin 

 Museums, without which I could not have accomplished my task. 



This family belongs neither to the beginning nor to the end of 

 the eels, but to the Salmonoid abdominals, of which it constitutes 

 the least-organized family, and is an analogue of the eels. The rays 

 of the pectoral and anal fins, and when the caudal fin is present of 

 it also, are jointed or divided. 



It is composed of the following five genera : — 



1. Sternarchus (Schn.), havin^ a small caudal fin. 



'2. Rhamphichthys {M. & Tr.), having a small, toothless mouth. 



3. Sternopygus [M. <& Tr.), having a small mouth armed by nu- 

 merous rows of card-like teeth. 



-i. Carapus [M. S Tr.). Scaly fishes, with a row of pointed teeth, 

 and no caudal fin. 



5. Gymnotus, Linn. Destitute entirely of scales. 



Genus 1. STERNARCHUS, 5c/i?ie/(7e/-. 



Diagn. Having a small, normally-formed caudal fin. 



Descr. Teeth on the premaxillaries and fore border of the man- 

 dible, which form two clusters above, and two rows pointing back- 

 wards below. No teeth on the symphysis. Head and l)ody laterally 

 compressed. Head naked. Body scaly. On the middle of the 

 dorsal aspect of the tail there exists a thong, which, in the living 

 fish, reclines in a furrow wherein it is fixed by mucus.* Anus 



* This can only be likened to the adipose fin of the Salmonidie, when that is 

 elongated into a filament. 



