64 MR. C. TATE REGAN ON [May 12, 



dorsal and anal spines and of the pectoral, the number of rows of 

 scales between the lateral line and the sheath at the base of the 

 dorsal fin, and the number of anal rays, III 7 or III 8. Messrs. 

 Jordan and Evermann give the number of anal rays for one 

 species as III 7-8, but I have been unable to find a single case 

 throughout the genus where the number of anal rays is variable 

 in a species, and there is good reason for supposing that in this 

 instance two difierent species have been confounded. The same 

 authors regard G. patao Poey as identical with 'G. brasilianus 

 Cuv. & Yal., which is said to be only doubtfully distinct from 

 G. Ii7ieatus Humboldt, in the synonymy of which G. axillaris 

 Giinther is included. Other species regarded by them as valid 

 are G. brevimanus Giinther, G. pliomieri Cuv. & Val., G. embryx 

 Jordan &, Starks, and G. mexicanus Steind. 



After examining all the available material in the British 

 Museum Collection and i-eferring to the original descriptions, I 

 have arrived at conclusions somewhat different from those of the 

 authors above mentioned, and the relations of the American 

 species of this section which I regard as valid are shown in the 

 following key and short revision : — 



Prseorbital and prEBoperculiun serrated ; dark longitudinal lines along the rows of 

 scales. 



I. Anal with III 8 rays. 



A. Pectoral it length of head 1. (?. 5)'e«j)»awMs Giinther. 



B. Pectoral as long as or a little longer than head. 



a. Second dorsal spine as long as or a little 

 longer than head. 

 Second anal spine | length of second dorsal spine ... 2. ff. plumieri Cnv. & Val. 

 Second anal spine I length of second dorsal spine ... 3. G. mexicanus Steind. 



h. Second dorsal spine f— ^ length of head. 

 About 15 gill-rakers on lower part of anterior arch ,. . 4. G. lineatus Humboldt. 

 About 12 gill-rakers on lower part of anterior arch .. . 5. G. axillaris Giinther. 



II. Anal with III 7 rays 6. G. patao "Poey. 



Gerres brevimanus Giinther, 



This species is at once distinguished by its short pectoral ; the 

 body is a little less elevated than in its allies ; second anal spine 

 -i the length of second dorsal spine, which is 4 the length of head ; 

 11 very short gill-rakers on lower part of anterior arch. 



A single example from Chiapas, West coast of Mexico. 



Gerres plumieri Cuv. & Val. 



The elongate second dorsal spine and the second anal spine 

 nearly as long are diagnostic ; pectoral as long as head or a little 

 longer; 13-14 very short gill-rakers on lower part of anterior 

 arch. 



Atlantic coasts of Tropical America. Lake Yzabal. 



Gerres mexicanus Steindachner. 



This species, from the E. Teapa, apparently difiers from the 

 preceding only in the shorter second anal spine. 



