JURA. NATURAL HISTORY. 187 



from the P. marinus in having fewer teeth, in the 

 presence of the bony bodies which surround the throat, 

 in colour, and in the absence of the dorsal stains. 



In size it approaches to the P. fluviatilis, which it 

 also resembles in the proportion and disposition of the 

 fins ; but it differs materially in the absence of the 

 annuli, in the greater number of the teeth, and in the 

 number and forms of the bony bodies which surround 

 the opening of the throat. 



With regard to its distinctions from the remainder 

 of the genus, they are so numerous as to require no notice. 



From the situation in which it was taken, it might be 

 considered as a parasitical fish ; particularly as the P. 

 branchialis is in the same way found attached to other 

 fishes. But the evidence is too limited to justify such 

 a conclusion. 



The following definition seems necessary to distinguish 

 it ; although, without so tedious an enumeration of cha- 

 racters, its figure and habitation would serve to prevent 

 it from being confounded with those to which it ap- 

 proximates in verbal description. 



P. Ordinibus dentium plurimis ; quatuor majoribus 

 obtusis prope fauces ; corpore non annulate ; pinna 

 dorsali posteriore caudse adherente. 



From the place where it was found, it may be called 

 Petromyzon Jurae. 



Some marine animals occur in these seas which remain 

 still unrecorded in the catalogue of British zoology. 

 Among these indeed it is probable that a few will be 

 found still undescribed by naturalists ; since fresh addi- 

 tions are even yet occasionally made to our catalogue 

 of these obscurer parts of the creation. Many of these 

 animals have occasionally fallen under my notice, but 

 amid pursuits which rendered it impossible to attend either 

 to their examination or preservation. I have however 

 preserved a memorial of one, as it appears to form a new 

 species in a tribe of which no individual has yet been 



