PLATE 1 



EXPLANATION OF FIGURES 



1 Outline from life of P. gemellipara somewhat flattened under a cover 

 slip. Several stages of emljryonic development shown within capsules X 64. 



2 Three animals natural size and five others X 5 in characteristic shapes and 

 poses. 



3 The entire animal viewed from the left side as a semi-transparent object. 

 To show particularly the position of the reproductive organs and their relation 

 to other organs. X 8S. 



4 Frontal section through the upper end of the antrum femininum, the ends 

 of the vitellaria and the most mature oocytes of each ovary. X 200. 



5 A spermatozoon. X 606. 



6 Youngest third of the ovary to show the oogonia, development of the nu- 

 cleolus, and particularly the development of the mitochondrial mass. X 606. 



7 Portion of an oocyte to show the structure of the cytoplasm and mitochon- 

 drial mass. X 606. 



ant.d', antrum masculinum 



ant., antrum femininum 



at., atrium commune 



br., brain 



cap., capsule 



cyt., cytoplasm 



e., eye 



gl.c, cephalic glands 



gl.sh., shell glands 



g.p., genital pore 



int., intestine 



m., mouth 



nies., mesenchyme 



niit., mitochondrial mass 



nal.s., natural size 



n.op., optic nerve 



nuc, nucleus 



nucl., nucleolus 



0., ovary 



ooc, oocyte 



oog., oogonia 



ph., pharynx musculature 



S.V., vesiculum seminalis 



t., testis 



v.d., vas deferens 



vest., vestibule 



vit., vitellarium 



y.c, yolk cell 



540 



