or those of Lesueur of the same species with whieh 

 one may coinpare our figs.33 & 33. The part at 

 tached to the host at this stage is only threadliXe' 

 with a more or less distinct invagination at the 

 point where the aiidomen oegins, Of the two 

 smaller species, P.sagitta & P. varians, especially th 

 latter,we next have a series of very young forms,, 

 distinet larvae of only a few millimeters in length 

 and the most important steps in this development we 

 have sought to present in f igs.32 ,m,n,& o« 



While the forwatd end of the aoove mentioned 

 specimen,clinging to the host with a simple thread- 

 liXe hody,on the whole corresponds to the ful ly de- 

 veloped Pennella and has mouth-parts of the same fo 

 and structure as these,while the swollen head also 

 is of essentially the same form. Thus we see 

 that in this early stage, in which the oody of the 

 ourrowing guest has not yet penetrated into the hos 

 the head and mouth-parts are not yet transformed in 

 the strong attachment and anchor organs« 



If step "by step through our figures we follow t 

 development "back to the youngest stage (f ig.l .m.n,& 

 we have found,we may easily see in what way the mou 

 parts have graduaily developed and formed themselve 

 out of projections from the under surface of • the yo 



