106 



V 



niversity of California Puhlications in Zoology [Vol. 11 



2. An increase in length from 21 to 23 mm. is accompanied 

 with a relative decrease in length of ganglion of 0.17 per cent. 



3. An increase in length from 23 to 25 mm. is accompanied 

 with a relative decrease in length of ganglion of 0.09 per cent. 



These facts mean that the rates of increase in length of body 



and ganglion approximate closer to equality as the animal grows 



1 T iu J j-i i- length of ganglion . 



larger. In other words the ratio -^-^ — ; ~ — ° — r- is more 



length 01 animal 



nearly constant in the larger than in the smaller animals. 



Interval prom Anterior to Posterior Fin. — Table 4 shows 

 an absence of anv well-defined correlation. ^Moreover it is 



TABLE 4 

 CORKEI.ATION BETWEEN' LflXCTH OP An'IM.^L AND PrOPORTIOXAL INTERVAL 



FROM Anterior to Posterior Fin 



Proportional 



length of 

 interval from 

 anterior fin to 

 posterior fin 



Length of animal 



3 

 -0.1454 



evident that, excepting the two specimens whose lengths lie 

 between 12 and 14 mm., in the vast majority of all animals, 

 irrespective of length, this interval measures between 7 and 

 9 per cent. However, the following averages indicate that there 

 is at least a tendency for this interval to increase in length more 

 rapidly than the animal does, and that the negative coefficient 

 is probably due to the effect of those animals under 16 mm. in 

 length in which the interval seems to be larger. These averages 

 are as follows : 



