GREAT LAKES COREGONIDS 



437 



of development of the sex organs is at times, therefore, a systematic character in 

 differentiating certain specimens. 



A discussion of the differences between Jciyi and johannx, alpenas, zenithicus, and 

 reighardi is given on pages 352, 365, 390, and 402. 



GEOGRAPHICAL DISTRIBUTION 



All my records on the occurrence of the kiyi are assembled in Table 48 and are 

 platted on the chart in Figure 4. They are 22 in number, and all but two (which 

 were made from the trout nets) are from examinations of the commercial chub hauls. 

 They show that the species has been taken out of all the ports visited, and it may 

 be concluded that it is distributed generally throughout the lake where suitable 

 conditions obtain. 



BATHYMETRIC DISTRIBUTION 



All the records of the vertical distribution of the kiyi are derived from an exam- 

 ination of the 23^2 and 2% inch chub nets, which are set at varying depths in the 

 lake, and the 43^-inch trout nets, usually set in less than 40 fathoms. The shallowest 

 gang tba"t took Tciyi was of chub nets set in 20 to 35 fathoms (record 7) and of 43^-inch 

 nets set in 28 to 32 fathoms (record 16), and the deepest in chub nets from 71 to 90 

 fathoms (record 2). In the lifts from shallow water the species was rare, but it was 

 distributed throughout the extent of the deepest gang. It is certain, then, that the 

 species comes into water as shallow as 30 fathoms and possibly shallower, though it 

 never has been seen from the 1 3/2-inch nets set in 26 to 40 fathoms (seep. 354), and 

 it descends into depths of 90 fathoms and probably deeper. 



RELATIVE ABUNDANCE 



The data on relative abundance of the kiyi are only approximate. Fish were 

 very rare in the 23/2 and 2% inch nets in 1920 (see p. 354) ; and the kiyi, being a small 

 species, is not taken so abundantly in the 2%-inch nets as in those of smaller mesh, 

 so that the percentages of abundance are lower necessarily for the lifts of the 2%-inch 

 nets. The data, however, all bear the same aspect and probably indicate what would 

 be the result of more careful investigation. 



No Tciyi occurred in the lifts of the 2% to 2% inch nets made in Green Bay on 

 August 16, 1920, off Little Sturgeon and 8 miles south of Green Island in 11 and 16 

 fathoms, and on August 18, 1920, 4 miles west of Boyer Bluff in 18 to 24 fathoms; 

 in Lake Michigan proper on June 22, 1920, off Cathead Light in 40 to 60 fathoms; 

 on August 10, 1923, 8 miles NNW. of Big Rock Point, Mich., in 45 to 50 fathoms; 

 on March 24, 1919, in an unknown location off Milwaukee, Wis.; on September 

 24, 1920, 9 miles NNE., and on November 15, 1920, 20 miles ESE. of Milwaukee, Wis., 

 in 50, 22 to 25, and 28 to 35 fathoms, respectively; on November 19, 1920, 10 miles 

 NNW. of Michigan City, Ind., in 18 fathoms, and 17 miles NNW. in 28 to 32 fathoms, 

 and 17% miles NW. by N. % N. in 32 fathoms; on March 2, 1921, 21 miles NNW. 

 and on March 4, 1921, 15 miles NW. by N. Y 2 N. in 28 to 30 fathoms. The Novem- 

 ber lifts were made on or near the spawning grounds of zenithicus and the March 

 lifts on the spawning grounds of hoyi, so that the absence of Tciyi is not so surprising; 



