372 



BULLETIN OF THE BUREAU OF FISHERIES 



Pv/P: 



alpense, (1.6) 1.8-2 (2.2), with 85 per cent more than 1.7. 

 kiyi, (1.1) 1.4-1.7 (1.9), with 4 per cent more than 1.7. 

 Av/V: 



alpense, (1.1) 1.3-1.5 (1.7), with 93 per cent more than 1.2. 

 kiyi, (0.9) 1-1.2 (1.4), with 6 per cent more than 1.2. 



The proportions involving the head and eye may be taken only to indicate 

 a general trend, as of the two groups of specimens compared the alpense averaged 

 3 centimeters larger. The maxillary is almost always immaculate in alpense and 

 is almost always pigmented over at least half its surface in kiyi. The back, also, is 

 darker on the average in the latter. The mandible in alpenx is less pigmented and 

 more powerful than in kiyi, and the body shape is more elliptical as seen from the 

 side. A discussion of the difference between alpenx and hoyi may be found on 

 page 461. 



From artedi, alpenx may be distinguished by the character of the mandible, 

 which in alpenx is well developed, pale, and longer, as a rule, than the upper jaw, 

 and in artedi frail, more or less conspicuously pigmented, and usually shorter; by 

 the fewer gill rakers on the first branchial arch and the longer head, snout, and 

 maxillary. A detailed comparison of the technical characters follows: 



Gill rakers on the first branchial arch : 29 



alpenx, (31) 34-40 (44), with 16 per cent more than 39. 



artedi, (40) 45-50 (53). 

 L/H: 



alpenx, (3.6) 4-4.3 (4.4). 



artedi, (4) 4.3-4.6 (5), with 57 per cent more than 4.4. 

 H/M: 



alpenx, (2.3) 2.5-2.6 (2.8), with 7 per cent more than 2.6. 

 artedi, (2.6) 2.8-3 (3.3), with 96 per cent more than 2.6. 



H/S: 



alpenx, (3.1) 3.4-3.6 (3.8), with 7 per cent more than 3.6. 

 artedi, (3.5) 3.7-4 (4.3), with 82 per cent more than 3.6. 



Alpenx also shows much less pigmentation, especially on the dorsal surface 

 and on the maxillary. The latter usually is immaculate in alpenx and always 

 pigmented in artedi. 



GEOGRAPHICAL DISTRIBUTION 



In Table 22 are brought together all my data on the occurrence of the longjaw 

 in Lake Huron. Figure 5 shows these data platted on the chart of Lake Huron. 



Lake Huron proper. — With the exception of entries 5, 40, 41, 42, and 45, the 

 45 records for Lake Huron proper were made by me from boats entering the harbors 

 in Michigan of Cheboygan, Rogers, Alpena, and Harbor Beach. The location in 

 the lake from which these lifts were made is shown on the chart. (Fig. 5.) Twenty- 

 eight of these records are from the boats that used the 2%-inch nets suitable for 

 chubs, and the rest are from the 4J^ or 13^ inch gill nets and pound nets set for 

 other species or from special 2%-inch nets. Commercial fishing operations thus 

 indicate that the longjaw is found in the deeper American waters from about the 



" Figures for gill rakers are given for all specimens. The rest are given for specimens 210 millimeters or more in length in the 

 > of alpense, and 225 millimeters or more in length in the case of artedi. 



