PHYLUM MOLLUSCA 



801 



the eyes ; and still nearer the vegetal pole a series of paired 

 elevations, the rudiments of the arms. 



6 



FIG. 701. Two later stages in the development of XiOligo. A, from the funnel side. B, obliquely 

 from above. Letters as in preceding figures ; ne. cart, nuchal cartilage. (After Korschelt and 

 Heider.) 



FIG. 70-2. Two stages in the development of LoligO, later than those represented in Fig. 701. 

 From the anal or funnel side. Letters as in preceding figure ; in addition, fin, fins. (After 

 Korschelt and II eider.) 



After the complete enclosure of the yolk by the blastoderm, the 

 mouth (mo.) is developed as an oval depression between the rudi- 



