262 SILVERY LAMPREY. 



being specifically different : it is said to be found 

 only at those times in which the Shad (Clupea 

 Alosa) is in the river : these fishes it persecutes, by 

 fastening beneath their bellies, and sucking their 

 blood with the avidity of a Leech ; its body beirig 

 constantly found full of that fluid alone : they 

 sometimes attack Salmon in a similar manner, but, 

 from the greater thickness of the skin in those 

 fishes, are able to obtain but a small quantity of 

 blood from them. 



SILVERY LAMPREY. 



Petromyzon Argenteus. P. corpore argenteo nitido, dorso sub- 



Jiavescente. 



Lamprey with bright silvery body^ and slightly yellowish back. 

 Petromyzon corpore argenteo. Block. (. 415./. 2. 



Length of the specimen described by Dr. Bloch 

 about six inches : general appear anc^^ that of the 

 minute lamprey ; colour bright silvery, with a 

 yellowish brown tinge on the upper parts : mouth 

 ' large : teeth orange-coloured, and situated in the 

 fore part of the mouth : eyes very large, with 

 silvery irides : both the dorsal fins very shalloW;^ 

 and without any angular outline : lateral line very 

 distinct : tail lanceolate. Native of the Indian 

 seas. 



