MAY, 1902. THE ICHTHYOLOGY OF MEXICO MEEK. 79 



at Patzcuaro and was unable to detect more than one species. 

 Eighteen specimens in our collection show considerable variation. 

 I am inclined to believe that the two species described by Dr. 

 Steindachner are the same. Spawning time the last of May or 

 early in June. Patzcuaro. 



KEY TO THE SPECIES OF ALGAXSEA. 



a. Scales large, fewer than 56 in the lateral series. SALLEI. 

 aa. Scales smaller, more than 60 in the lateral series. 



b. Gill-rakers short and blunt, 15 to 19. 



c. Gill-rakers 3 -(-12; dorsal fin inserted over ventrals. 



TINCELLA. 



cc. Gill-rakers 4-1-15; dorsal fin inserted slightly before vent- 

 rals. DUGESI. 

 bb. Gill-rakers longer and slender, 22 or 23 on first gill arch. 



d. Scales larger, 65 in the lateral series. RUBESCEXS. 

 dd. Scales small, 85 to 94 in the lateral line. LACUSTRIS. 



Pimephales confertus Girard. 



Length of largest specimens 2.76 in. 



This species is quite abundant in Northern Mexico. It is 

 even more variable than its northern relative, Pimephales promelas. 



On the upper half of the body of small specimens (less than 2 

 inches in length) are narrow vertical (slightly inclined backward) 

 dark streaks, which are usually much branched. These also 

 appear on larger specimens, but in much smaller numbers. 



A few of the -males from Santa Rosalia are almost black. 

 These have a light vertical bar on shoulder crossing base of pec- 

 toral fin, and a second bar on middle of body crossing base of 

 ventral fin. Pectorals black; ventrals and anal black, edged 

 with white. The caudal fin is light with a broad black bar 

 across its middle: on lighter colored males the fins are less 

 dark, and there are no cross bars on sides of body. 



Many of the males have tubercles on the end of the snout. 

 This species is more chubby than Pimephales promelas ; it also has 

 smaller scales, 52 to 55 in the lateral line, instead of 43 to 47. 

 There is some difference in the markings on the males. The lighter 

 males and females have a dark lateral band which does not end 

 in a dark caudal spot. This band is more distinct on smaller 

 specimens. Usually the anterior portion is partially concealed 

 with a dash of red; under side of head and breast with some red. 

 Longest specimen, 2. 76 inches in length. 



