1911] Michael: Ckaetognatha of the San Diego Region. 55 



tion of S. vougae, the formula of which is 9, 4-5, 6-7. However, 

 the San Diego specimen is very immature, having not the slightest 

 trace of ovary or seminal vesicle. 



TABULATION AND DISCUSSION OF THE LENGTH OF OVARIES 

 IN SOME OF THE SAN DIEGO SPECIES OF CHAETOGNATHA 



In the following tabulations I have attempted to arrange the 

 specimens of each species in several groups according to maturity 

 of the ovaries. Such a separation is almost entirely a matter 

 of judgment depending upon a combination of characters which 

 baffles exact definition. Length and width of ovary, size and 

 appearance of eggs, tumidity of seminal receptacles, and size of 

 animal are some of the factors that influence judgment concern- 

 ing maturity, but it is as impossible to define the value of each 

 with respect to the others as it is to define exactly the value of 

 each feature, expression, or mannerism that makes you sure of 

 your acquaintance with a friend. I have, then, separated the 

 stages of maturity, fully realizing the impossibility of stating the 

 exact reason for placing this individual as mature and that one 

 as only approaching maturity. But, crude as it may be, only by 

 such a separation is it possible to consider variations of the 

 mature ovary within a single species. 



I have noticed that, in some species, the seminal vesicles and 

 ovaries mature at the same time, while in other species their 

 development is not parallel. In order to prevent the possibility 

 of prejudice in associating the mature ovary with the mature 

 seminal vesicle, the method of making tabulations has been as 

 follows : The first entry concerned the maturity of the ovary • 

 after this was settled, measurements of the ovary were made 

 with an ocular micrometer and recorded. The specimens were 

 then numbered, isolated, and laid aside for at least a week. 

 Having by that time entirely forgotten what the measurements 

 were, I entered on another sheet of paper, against the number 

 of my specimen, my judgment concerning the maturity of the 

 seminal vesicles. The results were then brought together, the 

 measurements reduced to millimeters, and the data arranged as 

 in the following tables. 



