GREAT LAKES COREGONIDS 



407 



It appears, thus, that the Nipigon race has fewer scales in the lateral line and 

 fewer scale rows and somewhat fewer rakers, more dorsal rays, a proportionally 

 longer head, snout, maxillary, and paired fins, and a proportionally smaller eye, and 

 a deeper body. The premaxillaries also are less vertical in position. The two forms 

 are alike as concerns body shape, as seen from the side, in having an included lower 

 jaw (though in dymondi the mandible is proportionally longer and not so invariably 

 included), and in the small size attained. (Extreme examples obtained after exten- 

 sive collecting in virgin waters measure only 304 millimeters.) 



This form appears sufficiently distinct to merit a name and is here designated as 

 dymondi. The type is specimen No. 57467, described in detail in Table 35. It is 

 catalogued as No. 88353, U. S. National Museum. 



Living specimens are paler in color than those from Lake Michigan, and pre- 

 served specimens show reduced pigment. The prenarial area is not conspicuously 

 darker, and -the mandible tip is never black. The maxillary may be immaculate 

 occasionally and frequently is pigmented over only one-fourth its surface; the paired 

 fins and the anal are frequently immaculate. Usually, however, there is at least a 

 rim of pigment on the dorsal edge of the pectorals, and sometimes there is pigment on 

 them all. 



One male specimen collected on July 26, 1922, showed traces of pearl organs, 

 and it is likely that at least all males develop them in the breeding season. 



VARIATIONS 



Racial variations. — There are not sufficient specimens available for examination 

 to determine whether there are intraspecific variations. 



Size variations. — In Table 35 are compared extensively 10 specimens more than 

 200 millimeters in length and 9 specimens 200 millimeters in length or smaller. A 

 few small fish are compared with larger ones for several characters only in Tables 

 8 to 11. Small fish seem to have a proportionally larger eye, shorter snout, and less 

 body depth. The base of the dorsal and of the anal and the gill rakers also appear 

 to be somewhat longer, and the dorsal and anal rays are less in the small fish, though 

 the lower number of rays no doubt is due to the exclusion from the individual counts 

 of one of the first rays, which are apt to be shorter in small specimens. 



The few specimens examined indicate that individuals that have attained a 

 length of 170 millimeters by the middle of the summer are sexually mature. 



comparisons 64 



The low gill-raker count will distinguish reighardi from any of the Nipigon Leu- 

 cichthys except zenithicus. A discussion of the differences between reighardi and 

 zenithicus is given on page 386. 



Reighardi differs from nigripinnis regalis in having a much more elliptical body shape 

 (seen from the side), a shorter, more included mandible, a much paler body and 

 fins, and a smaller eye. The comparative figures for gill rakers and eye size follow: 



Gill rakers on the first branchial arch : 



reighardi, (32) 33-36 (38). 



nigripinnis, (44) 48-51 (54). 

 H/E: 



reighardi, (3.6) 4-4.4 (4.8), with 44 per cent more than 4.1. 

 nigripinnis, (3.5) 3.7-4.1 (4.3), with 5 per cent more than 4.1. 



m The specimens in this section compared for proportions are those 200 millimeters or more in length, except in the case of artedi 

 where they are 225 millimeters or more. The counts are given for specimens of all sizes. 



