I.EPTOCEPHALIDiE. 143 



Family I. LEPTOCEPHALIDJ^, Boiuqnute. 



Helmichtliydie, KoUiJccr. 



Small, generally leaf-like, compressed, transparent fish, entirely 

 devoid of scales, whose lateral line is formed by the intersections of 

 the lateral muscles. 



Some groups of the family have teeth, others are toothless, some 

 have pectoral llns, and others want these members. The intestinal 

 canal runs along the inferior edge of the belly, and terminates in 

 the anus, either before or behind the middle of the fish. The 

 skeleton is very imperfect and cartilaginous, and the brain shows 

 through it. Most of the family possess a pointed, or blunt, but 

 rarely a forked caudal fin, at the confluence of the dorsal and anal, 

 from which it is to be distinguished by the form or size of its 

 rays. 



Ichthyologists have compared these fish correctly with earthworms 

 or tapeworms. They have evidently an inferior organization to the 

 Anguilliform lishes, inasmuch as their vertebral column is cartila- 

 ginous only. Though I have to describe a considerable number of 

 new species, yet I believe that very many have escaped ray notice. 

 Of the European forms, that is to say, of the Sicilian ones, there 

 remain numbers not in my list, and the genei'a Oxystomiis, Pterurus, 

 and Oxiiurus of Rafinesque still need to be re- discovered and pro- 

 perly characterised, or to be recognised as synonymous with some of 

 the described species. 



Genus 1. ESUNCULUS, /laup. 



Diat/n. Leptocephali, with small ventral fins and forked caudals. 



Dcscr. Like the Leptoccphali in their transparency, in their late- 

 ral line, formed by angular, interrupted, transverse lines, in the 

 position of the intestinal canal along the ventral border, in the anus 

 placed far back, and in the rows of black points ranged along the 

 gut. The teeth of the upper jaw are short and straight, while those 

 of the mandible are longer and obliquely inclined forwards, as may 

 also be observed in many toothed Leptoccphali. That which par- 

 ticularly distinguishes this genus are the small, five-rayed, ventral 

 fins, situated in the middle of the fish, the oblique anal and dorsal 

 fins opposed to one another, and the forked caudal, whose rays are 

 jointed. These characters place this form at the head of the Jjepto- 

 cephalida, and indicate that family as the lowest of the Abdominal 

 fishes. The name of the family is derived from the miniature like- 

 ness of its members to the Pikes [Esox.). I first saw this inte- 

 resting genus in the Paris Museum, where it is kept under the 

 erroneous appellation of Helmichthys of Rafinesque ; and we may 



