448 Simon Heiiry Gage 



agrees with the teleosts and the ganoids, so far as they have 

 been investigated (Calberla, '77, Balfour, '81). Other refer- 

 ences to the embryology of the lamprey will be found in the 

 bibliography at the end. 



In nature the young larvae live in the sand in the bottom of 

 the nest where the eggs were deposited by the parents. Some- 

 times the larger ones are found most abundantly in the sand 

 and gravel under the pile of stones bordering the lower edge 

 of the nest. This may have given rise to the prevalent notion 

 that the pile of stones is the real nest. One can obtain the 

 embryos very easily by shoveling up the sand from the bottom 

 of a nest. If water is then added to wash away the mud, and 

 the sand is shaken lightly, the eggs or embryos or both appear 

 on the surface, and are readily detected by the light color of 

 the eggs or the greenish color of the food yolk in the embryo 

 of 8 to 10 millimeters. After the larvae are 10 to 15 milli- 

 meters in length it is far more difficult to secure them as they 

 are less conspicuous and far more active. Then too, they ex- 

 hibit already the habits of older larvae and very quickly dis- 

 appear in the sand. 



The exact time the larvae remain in the nest and the stage 

 of development reached by them before leaving it is not 

 known with exactitude. Already on July 31st, larvae 30 mm. 

 long were found while searching for large larvae. A few days 

 later a thorough exploration was made by my assistant, G. S. 

 Hopkins, D.Sc. both in the nests and in the sand banks at 

 the concavity of the stream where the larger larvae are found 

 throughout the year (PI. VII, fig. 40). None could be found 

 in the nests at the bottom of the stream, but in the sand at 

 the side of the stream many of all sizes were obtained, some 

 of them being only 16 millimeters in length. Consequently 

 it is believed that the larvae remain in the nests only about 

 one month or until they attain a length of 12 to 15 milli- 

 meters. Whether they voluntarily leave the nest or whether 

 the rapid current of some sudden rise in the stream, as after a 

 heavy storm, washes them out of the nest is not known. It 

 is believed, however, that they leave the nest voluntarily, for, 

 on account of the conformation of the nest, any moderate in- 



