30 REPOET OF COMMISSIONER OF FISH AND FISHERIES. 



Brevoortia pectinata. 



42. The following is au exact description of Jenyns species of Bre- 

 voortia from the Atlantic coast of Paraguay and Patagonia : 



BB'evoortSa peclfinata (Jenyns) Gill. Darwin's MenhADEN. 



Diagnosis, — Proportions of head and jaws as in B. tyrannus. Height 

 of body almost three-eighths of total length, and greater proportionally 

 than in B. tyrannus. Fins nearly as in B. tyrannus, but uniformly 

 averaging slightly more; the height of the dorsal somewhat less than 

 three-twentieths of total length ; that of the anal equal to or slightly 

 less than half the length of the maxillary. The caudal fin is somewhat 

 longer and more furcate; the length of the external rays never being 

 less than five-sixths of the length of the head, while that of the medial 

 rays remains proportionally the same as in the species first described. 

 Insertion of ventral somewhat behind tip of pectoral, this fin and this 

 dorsal being uniformly somewhat farther back than in B. tyrannus ; the 

 insertion of the latter from one to four one-hundredths posterior to a 

 point equidistant from the snout and the base of the median caudal rays, 

 and, as in B. tyrannus, behind the vertical from the insertion of the ven- 

 trals. 



Scales very large, considei^ably serrated, and arranged regularly in 

 18-20 transverse and 50 longitudinal rows. 



Scales forming sheath at base of pectoral not large. Operculum 

 smooth or with inconspicuous and few striations. Squamation upon 

 lobes of caudal extensive and conspicuous. 



Variations. 



The variations in the individual specimens studied are not of great 

 importance, and are indicated in the tables of measurements. 



TahJe of measuremenls. 



