478 



Geoffrey Smitli 



Siimmary. 

 Wc luay tabulate tlic life-bistory of G. inaxülaris as foUows: 



Normal seginented larvae 

 0,8—1,2 mm. 



Pranizae on fish 

 1 — 1 mm. 



Small adults on ground. 



Giant segmented larvae 

 on ground 4—5 mm. 



Pranizae on fish 

 5 — 8 mm. 



Large adults 

 on ground. 



The points tliat remain uncertain are: (I.) Whetlier segmented 

 larvai stages can be interpolateli at various points in the larvai 

 history. It is true that this happens to a certain extent, as seg- 

 mented larvae of various sizes are met with in very small numbers, 

 but it is probable tbat this is only the general rule when the Pra- 

 nizae are l)rushed uff from their hosts measuring about 4 to 5 mm. 

 (2.) Tlie fate of the giant segmented larvae remains doubtful, but it 

 is bigbly probable that if they can succeed in attaehing themselves 

 to another fish they will develop into large Pranizae, as indieated 

 by the arrow in the diagram. 



The Chief theoretical interest of the life-history is that differences 

 in the length of the larvai life and in the amount of nutrition taken 

 in (luriug this period, whether under the control of hereditary ten- 

 dencies or not, lead to very great differences in the size of the 

 adults and to an incipient dimorphism in the secondary sexual 

 characters of the males. Further there is a very decided tendeucy 

 towards the establishment of two modal conditious corresponding to 

 the two kiuds of males. 



Naples, Zoological Station, February 1904. 



