SCHAFFNER ON THE OCCURRENCE OF AMMOCOETES. 71 



NOTES ON THE OCCURRENCE OF AMMOCOETES, THE LARVAL 

 FORM OF LAMPETRA WILDERI, NEAR ANN ARBOR. 



BY DANIEL C. SCHAFFXKU. 



Lampetia wikleii, the common brook lamprey of this region, occurs 

 in small streams tributary to the Huron river. It has been reported as 

 abundant during the breeding season from a number of points near 

 Ann Arbor, but previous to October 1900 the larval form had not been 

 taken near here. 



In the spring of 1899 Robert T. Young and Leon J. Cole of the 

 University made a study of the nesting habits of Lampetra wilderi in 

 Honev Creek, a small tributary of the Huron river, about four miles 

 west of Ann Arbor. From this same stream the Ammocoetes were 

 secured last October. Young and Cole made their observations form 

 April 15 to 20 inclusive, and during that time a large number of the 

 lampreys appeared, built their nests, laid their eggs, and disappeared. 



In a brief jjaper on the Transformation of the Brook Lamprey, Prof. 

 Simon H. Gage, of Cornell, states that brook lampreys die after the end 

 of the breeding season and that they are not parasitic in their habits, 

 their full size being attained during their larval life. The breeding 

 sseason lasts about two weeks. After hatching the young remain in 

 the nest until they are from twelve mm. to fifteen mm. in length. 

 This size is attained about the eighth week after the eggs are laid. 

 On leaving the nest the young wander down stream until they find 

 a quiet sandy place and there they buirow and remain until they are 

 fully developed. 



The most favorable place for finding the larva) is in the sand in any 

 quiet portion of the bed of the stream where the water is from three 

 to ten inches deep. Gage advises the use of a shovel for removing the 

 sand from the stream and states that the Ammocoetes can be secured 

 easily from the sand thrown on the bank; but we found this method 

 of taking them quite unsatisfactory as they persisted in wriggling out 

 of the sand and escaping into the water before we could land them on 

 the bank. We found tliat with a strong dip net frame to which an 

 ordinary bolting sack had been attached the sand could be scooped 

 up readily and after emptying the contents of the sack on the bank 

 the Ammocoetes were found at the bottom of the pile of sand. Pouring- 

 water on the sand after it was spread out on the grass caused the 

 Ammocoetes to wriggle about and so make themselves more conspicuous. 



\Vith a strong, long handled diji-net one can stand on the bank dry 

 shod and collect Ammocoetes in abundance. ^Ir. Reade. Mr. ^Michael, 

 and the writer used this method a part of one afternoon and succeeded 

 in taking fourteen Ammocoetes ranging in length from five to twelve cm. 



Since this paper was read we have taken scA'eral dozen more of the 

 lai'va^ ranging in lenglh from three to twenty cm. The larva' taken 

 a few days preceding the breeding season can be grouped under three 



