i8o 



WHITMAN. 



[Vol. I. 



EXPLANATION OF PLATE V. 



c, coelom. 



e«, entoderm. 



ef, epidermis. 



g, lateral ganglia. 



gl, larval glands. 



Ic, longitudinal commissures. 



m, mesoderm. 



m' ■, lateral cell-row. 



«c, nerve-cord — neural rows. 



nph^ nephridial rows — nephridia 



Reference Letters. 



oe.c, oesophageal collar. 



5, septum. 



sb,' anterior pair of sense-bulbs. 



sb," posterior pair of sense-bulbs. 



sex, sexual cells. 



sp, somatopleure. 



spp, splanchnopleure. 



5^, mouth. 



st.d, stomodseum. 



y, jolk. 



Fig. 8. C. parasita. Surface view of the embryo when the germ-bands 

 are about two-thirds closed. 



Figs. 9-11. Three portions of a horizontal (frontal) section of the embryo, 

 after the complete closure of the germ-bands, showing different stages in the 

 development of the neuronephric stratum. Fig. 9, near the end of the first 

 third; Fig. 10, near the beginning of the last third; and Fig. 11, very near the 

 hind end. X 280. 



Figs. 12-14. From a series of transverse sections of the head at time of 

 hatching. Fig. 12 hits the dorsal edge of the stomodseal ingrowth, and 

 grazes the anterior pair of sense-bulbs (51^") ; Fig. 13 is the next section above, 

 taking in a strip of the oesophageal collar and the centre of the sense-bulbs ; 

 Fig. 14 is the fifth section (= .0075™") above Fig. 13, and hits the posterior pair 

 of sense-bulbs (5^") ; j = the line of the yolk. The position of these sections 

 is shown by the arrows in Fig. 29. X 280. 



Figs. 15-19. Selected from a series of transverse sections through the hind 

 end of the embryo at time of hatching, showing an early stage in the develop- 

 ment of the nerve-chain and the nephridia. The sections run from near the 

 middle of one somite to the middle of the next in front. Fig. 15 gives the 

 first section; Fig. i6, the second; Fig. 17, the fourth; Fig. 18, the fifth; and 

 Fig. 19, the seventh. 



Fig. 18 is taken on the boundary line of the two somites. X 280. 



