492 



The Cyclostomes, or Lampreys 



narrow and toothless. From Professor Surface's paper on "The 

 Removal of Lampreys from the Interior Waters of New York" 

 \ve have the following extracts (slightly condensed) : 



"In the latter part of the fall the young lampreys, Petro- 

 iiiv^oii mariiuis iiuicolor, the variety land-locked in the lakes 

 of Central New York, metamorphose and assume the form of 

 the adult. They are now about six or eight inches long. The 

 externally segmented condition of the body disappears. The 



i^v 





Fig. 294. 



Fig. 295. 

 Mouth of Lake Lamprej-, 



Fig. 293. 

 Fig. 29.3. — Petronujzon marinus vnicolor (De Kay) 



Cayuga Lake. ( After Gage.) 

 Fig. 294. — Lampetra v:ilderi Jordan & Evermann. Larv 



burrow in a glass filled with sand. (After Gage.) 

 Fig. 29.5. — Lampetra wilda'i Jordan it Evermann. Mouth of Brook Lamprey 



Cayuga Lake. (After Gage.) 



brook lamprey in its 



eyes appear to grow out through the skin and become plainly 

 visible and functional. The mouth is no longer filled Avith verti- 

 cal membranous sheets to act as a sieve, but it contains nearly 

 one hundred and fifty sharp and chitinous teeth, arranged in 

 rows that are more or less concentric and at the same time 

 presenting the appearance of circular radiation. These teeth 

 are very strong, with sharp points, and in structure each has 

 the appearance of a hollow cone of chitin placed over another 

 cone or papilla. i\ little below the center of the mouth is the 

 oral opening, which is circular and contains a flattened tongue 

 Avhich bears finer teeth of chitin set closely together and arranged 

 in two interrupted (appearing as four) curved roAvs extending 



