1 86 CARL L. HUBBS. 



season was found to be still at its height about the middle of July v 

 but to have ended long before October 26. 



The breeding season of Micrometrus minimus in central Cali- 

 fornia apparently commences somewhat later than that of Am- 

 phigonoptcrus aurora. Of females taken in the same pool near 

 Piedras Blancas on June 2, those of Micrometrus contained 

 embryos from 4.6 to 18.7 mm. long, none ready for birth, whereas 

 those of Amphigonopterus contained embryos 12 to 34 mm. long, 

 the largest obviously ready for birth, being similar to numerous 

 young found at the same locality. A single female of Micro- 

 metrus collected at Point Purisima, California, on August 14, 

 was spent, but all of those taken during June still contained 

 young. Young showing considerable growth since birth were 

 taken in reef-pools of southern California early in July, suggest- 

 ing that the breeding season occurs earlier in the warmer waters 

 to the southward. 



SEX-RATIO IN ADULTS, YOUNG AND EMBRYOS. 



In the breeding pools poisoned near Piedras Blancas, the 

 females were found to be more numerous than the males, in the 

 proportion of nearly two to one: of those taken (by poison) and 

 sexed, 139 proved to be males; 264, females. 1 An unrecorded 

 observation by Dr. C. H. Gilbert on Cyniatogastcr aggregates 

 may have some bearing on this point : he has observed a single 

 male " herding about " several females. On the contrary I ob- 

 served several small fishes of the same species, presumably males, 

 accompanying a mating pair (Hubbs, 1917). However this may 

 be, the numbers of the sexes of the young fishes were found to be 

 approximately equal in two pools at different localities fished in 

 the autumn, after the close of the breeding season : in these two 

 pools, 83 young males and 82 young females were obtained. The 

 35 adult specimens of Micrometrus minimus obtained in a single 

 pool near Piedras Blancas comprised 19 males and 16 females. 



A more accurate sex-ratio can be obtained by determining the 

 sex of a series of embryos, by means of the secondary differences 

 in the anal fin, which become clearly evident very early in the 



i This difference in the sex-ratio may be determined by the greater lon- 

 gevity of the females. 



