Biological Survey — Oswego Watershed 



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fat and pigment cells is perfectly intelligible for all these were 

 torn away by the rasping tongue in order to reach the blood sup- 

 ply. But as stated, the principal bulk of the food in the intestine 

 was blood. Many other examinations showed the same to be true. 



Especial care was taken to determine the kind of food, for 

 various authors have stated that lampreys eat insects and worms, 

 the slime of fish and even small fish and fish eggs. The oesophagus 

 of the lamprey is not well adapted to the taking of any but liquid 

 food, and according to the easily verified researches of Vera 

 Mather,* there is a special grating over the entrance to the 

 oesophagus of the Pacific Coast lampreys (Entosphenus) which 

 would make the swallowing of insects, worms, etc., very difficult. 

 Neither is the mouth and rasping tongue adapted for the securing 

 of such food. The whole mechanism is adapted for securing and 

 swallowing liquid food, that is blood, and any minced muscle or 

 other finely divided tissue present in the intestine with the blood 

 is accidental, a by-product, so to speak, of the process for getting 

 the blood. 



Furthermore in confirmation that the natural food is blood it 

 was found the present spring, (1927) that all the lampreys have 

 special glands, buccal glands (Fig. 6), to produce an anticoagulat- 



Fig. 6.— Ventral view of the head and branchial region of a lake lamprey 

 to show the position of the buccal glands and the opening of their ducts. 

 BG. The bean-shaped, buccal glands at the level of the eyes (E). T. The 

 rasping tongue. D. The duct-opening of the left buccal gland. L. The 

 infraoral lamina. 1, 2, 3, 4, 5, 6, 7. The seven branchiopores or gill 

 openings on the left side. (From Science, Sept. 27, 1927). 



* Mather, Vera G. The velar apparatus of Entosphenus tridentatua 

 (Pacific lamprey). Anat. Rec. Vol. 34, 1926. 



