NO. l8 MENHADEN, GENUS BREVOORTIA — HILDEBRAND 9 



name tyrannus for this species, even though Latrobe ofifered no 

 description. 



Relationship. — B. tyrannus of the Atlantic is closely related to 

 B. patronus of the Gulf of Mexico. The relationship is shown in a 

 parallel comparison in the account of the last-mentioned species 

 (p. 20). 



Source oj the data and their presentation. — The proportions and 

 enumerations given in the follov^^ing paragraph are mostly based on 

 100 or more specimens and some of them on 200 or more examples. 

 In the range of proportions specimens less than 70 mm. in total length 

 were excluded because they were considered juveniles. The material 

 studied was collected at many places, from Massachusetts Bay (vi- 

 cinity of Boston) to Mayport, Fla. The range in the percentages of 

 the parts measured in the standard length is given first in each in- 

 stance, and this is followed by the number of times these same parts 

 are contained in the standard length or in the head, as the case may 

 be, enclosed in parentheses. 



Some proportions and enumerations. — Head 28 to 36 (2.75 to 3.5 

 in standard length), its depth 25 to 32 (3.1 to 4.0 in standard length) ; 

 depth of body 30 to 39 (2.55 to 3.3. in standard length) ; base of anal 

 14 to 19 (5.25 to 7.1 in standard length) ; lower lobe of caudal 25 to 

 35 (2.85 to 4.0 in standard length) ; caudal peduncle, depth 8.5 to 

 II (2.9 to 4.0 in head) ; eye, difficult to measure because of much 

 adipose tissue, about 5.5 to 8.3 (about 4.4 to 6.2 in head) ; snout 5.5 

 to 9 (3-9 to 5.5 in head) ; interorbital (bone) 6.2 to 8.2 (4.2 to 5.3 

 in head) ; maxillary 13.5 to 16.5 (1.9 to 2.'j in head) ; mandible 16.5 

 to 20 (1.7 to 2.0 in head) ; pectoral 17 to 20 (1.6 to 1.9 in head) ; 

 axillary appendage of pectoral variable, 8.0 to 15 (2.3 to 3.8 in head). 

 Dorsal rays 17 to 22 ; anal rays 18 to 24 ; pectoral rays 16 to 18, rarely 

 15 ; scales in oblique series crossing middle of side 41 to 55; vertical 

 series between tip of pectoral and base of ventral 3 or 4; modified 

 scales in a series in front of dorsal 31 to 43 ; ventral scutes 30 to 35 ; 

 gill rakers on lower limb of first arch increasing in number with age, 

 about 60 in specimens 60 mm. long, about 100 in specimens 100 mm. 

 long, about 140 in examples 200 to 250 mm. long, and 150 to 160 in 

 large adults 330 to 360 mm. long; vertebrae 47 to 49, rarely 45, 46 

 or 50 (enumerated in 194 specimens). 



Variation. — The range in many of the proportions and enumera- 

 tions given in the preceding paragraphs is rather wide. This results 

 in part frpm the many specimens used, and in part from the differ- 

 ences in examples from the various localities within the range of the 

 species. The proportions also are affected by the large range in size 



