402 



ZOOLOGY. 



430. Habits. None of the animal groups present habits 

 more interesting, more readily studied or more suggestive of 

 the adaptation of structure to the demands of the environment 

 than do the birds. The student will find by observation and 



FIG. 203. 



FIG. 202. Diagram Of the female genital organs of a Bird, c, cloaca; t, intestine; 

 k, kidney; o, ovary with ova of different size; od., oviduct; o.f., funnel of the oviduct; 

 o.o., opening of the oviduct into the cloaca; , ureter; u.o., opening of ureter into the 

 cloaca. Only one ovary and oviduct are fully developed in the Birds. 



Questions on the figure. What openings has the oviduct ? Why must 

 the union of sperm and ovum take place before the egg gets well down 

 the oviduct? Define the cloaca. On which side are the sexual organs 

 rudimentary in the female bird? 



FIG. 203. Diagram of the male urino-genital organs of a Bird, ad., adrenal body; 

 c, cloaca; i, intestine; k, kidney; t, testis; u, ureter; u.o., opening of ureter into the 

 cloaca; v.d., vas deferens; v.d.o., opening of the vas deferens; z'.s., vesicula seminalis. 



Questions on the figure. What is the function of the vas deferens? 

 Of the vesicula seminalis? What differentiates the cloaca from the in- 

 testine? What are the chief differences in the excretory organs of birds 

 and mammals? 



