146 CATALOGUE OF FISH. 



Length of the head . . . . . . 020 in. 



„ of the filamentous tail . . . . . 1"69 „ 



Height of the body 0-51 „ 



„ at the anus ....... 0'08 „ 



Length from point of the snout to the eye . . . 0'12 ,, 

 ,, „ to the pectorals . . 0'24 ,, 



Thickness of the body 0-04 to Q-QS „ 



head 0-06 to 0-07 „ 



Diameter of the black eyes ...... 0'05 „ 



Of Leptocephalus fiiamentosus, of Risso, I have been unable to 

 find either a description or drawing, and it must be a mere manu- 

 script name. It is probably the same with trich'mrus. 



4. TiLURUs Piissoi, Kaitp, fig. 6. 



Resembles trichiurus, but the tail is less hare-like, and the snout 

 less conical, yet more pointed. Twelve teeth in the upper jaw, nine 

 larger ones in the mandible. I know- of only one specimen, which is 

 in the Paris collection, and was found by Bibron at Messina in the 

 month of May. This example is, perhaps, defective in the tail, but 

 it may, with greater probability, be considered to be a species 

 having a less elongated, and not so hare-like a tail. 



Genus 4. LEPTOCEPHALUS, Linnaus. 



Distinguished from Tilurus by the tail not being prolonged in so 

 hare-like a form, and by the lateral muscular fasciculi being bent 

 angularly forwards. The genus includes species with and species 

 without teeth, species in which the teeth are imperceptible to the 

 unaided sight, and species whose teeth are proportionably stout, 

 very long, and pointed, and which may be readily seen by the naked 

 eye. Most of the species possess small pectoral fins, but there are 

 some without a trace of these members. It seems, as Costa has 

 already remarked, that all are without a distinctly-visible anal 

 opening, but have merely a most minute aperture, through which 

 the fluid excrement escapes from the extremity of the alimentary 

 canal. It is, therefore, only in fresh specimens, by pressing the 

 gut and looking at the extremity of the intestinal canal or begin- 

 ning of the anal fin, that one can discover the exact position of the 

 anus through the escape of the fluid. This is often impossible 

 with specimens that have been long immersed in alcohol. I have 

 referred the genus Helmictijs (better, Hehnichthys) of Eafinesque 

 to Leptoce])lial}LS, because, from its roundish form, it would be very 

 difficult to distinguish the two. It has the same structure of the 

 head and shape of body with Leptocejohalus, difTering from it merely 

 in its (jpinictatus) rounder form and more earth-worm-like habit, 

 while L. Spalanzani is more compressed. I cannot assent, there- 

 fore, to a generic distinction founded merely on a rounder body, and 



