452 



BULLETIN OF THE BUREAU OF FISHERIES 



length are compared in certain characters with those smaller. The size differences 

 being slight, no marked contrast is to be expected in the figures for the two classes, 

 but it does appear from the tables that the larger specimens have a somewhat smaller 

 head and eye and shorter paired fins. 



Individuals usually have been found to be maturing sexually at 140 millimeters.. 

 One specimen of 114 millimeters in length apparently was approaching sexuaL 

 maturity. 



COMPARISONS 16 



Hoyi most nearly resembles Jciyi. A discussion of the differences between the 

 two forms is given on page 436. The differences between hoyi and johannx, alpenae, 

 zenithicus, reighardi, and nigripinnis are given on pages 352, 366, 390, 403, and 419. 



Hoyi is distinguishable from artedi chiefly by the lower number of gill rakers 

 on the first branchial arch and of scales in the lateral line, by the larger head, longer 

 maxillary and ventral fins, and the length of the lower jaw, which in Jioyi is practi- 

 cally in all cases equal or longer than the upper but in artedi is equal or more often 

 shorter. Those characters that can be expressed numerically are compared below: 



Gill rakers on the first branchial arch: 



hoyi, (37) 41-44 (48), with 5 per cent more than 45. 



artedi, (41) 46-50 (55), with 86 per cent more than 45. 

 Lateral-line scales: 



hoyi, (60) 67-77 (84), with 7 per cent more than 77. 



artedi, (68) 77-87 (94) , with 88 per cent more than 77. 

 L/H: 



hoyi, (3.6) 4-4.2 (4.6), with 13 per cent more than 4.2. 

 artedi, (4) 4.2-4.5 (4.6), with 66 per cent more than 4.2. 

 H/M: 



hoyi, (2.3) 2.5-2.6 (2.8), with 16 per cent more than 2.6. 

 artedi, (2.4) 2.7-3 (3.1), with 86 per cent more than 2.6. 

 Av/V: 



hoyi, (1) 1.2-1.4 (1.7), with 8 per cent more than 1.4. 

 artedi, (1.3) 1.5-1.7 (2), with 93 per cent more than 1.4. 



In general hoyi has also a deeper, less terete body than artedi, particularly when 

 small, and the head, as seen from the side, is more sharply pointed. The body and 

 fins of hoyi are also less pigmented. The state of development of sex organs, espe- 

 cially in females, may often assist in separating individuals of the species, as hoyi 

 spawns in March and artedi in November. 



GEOGRAPHICAL DISTRIBUTION 



In Table 56 are given all my data on the occurrence of the bloater in Lake 

 Michigan. They are also shown platted on a map of the lake in Figure 4. There 

 are 53 observations made by me from the lj^-inch bait nets, which catch small 

 fish to bait the trout hooks; from the 4 to 4J^ inch trout and whitefish nets, the 

 1% to 2% inch chub nets, and from the pound nets. In the first two kinds of nets 

 only small individuals are taken usually, those in the trout and whitefish nets being 

 caught only accidentally by entangling their jaws in the netting. In the chub nets 



11 Figures in this section are given for all collected specimens, except the proportions for artedi, which are based on an examination, 

 of specimens less than 225 millimeters in length. 



O' 



