Sl'IllIFEll IIADIATCS Sowkkuy (Pauks oS2-:5SO) 



FiGUKK 9. — A cardinal view; showiiiij a similar st;is;o of dcvelop- 

 nieiit of the deltidiiiin ; from an individual which has not attained normal 

 fullti^rowtli. 



FiGUiJK 10. — The youngest growth-stage observed. 



FiGUUE lOri. — Outline profile of the same. 



FiGUKK 11. — Dorsal view of a normal adult. 



Figure 1U<. — Profile of the same. (28^// /Ihh. lU'pt. N. Y. Shite 

 Mus. Nut. Hist., pi. 24, figs. 2;3, 25.) 



ATPtYPA PJyiTCULAPxIS Linx.kus (Pages 350-300) 



Figure 12. — The incipient shell ; having a length of 2.25 mm. 'J'he 

 deltidial plates have already begun to form, and tlie shell has developed 

 two growth-lines. 



Figure 12*^?. — Outline profile of the same. 



Figure \'-\. — Ventral view of a full-grown iiidividunl. 



Figure 13a. — Profile of the same. (2s//( Ann. Iltpi. N. Y. State 

 Mus. Nut. Hist., pi. 25, figs. 40, 47.) 



Figure 14. — A series of outlines of the anterior margin of the valves; 

 sliowing the rapid increase in plications and the reversion from the em- 

 bryonic fold and sinus to the .><inus and fold of maturity. 



FiGUitE 15. — The deltidial characters of the specimen represented in 

 figure 12. 



FiGUUE l')(t. — Outlint^ profile of the same. 



Figure 10. — Similar view of a specimen measuring ■) X 3 mm. 



Figure 10a. — Outline i)rofile of the same. 



Figure 17. — Similar view of a specimen measuring 3.5 X 4 mm 



Figure 17a — Outline profile of the same. 



Figure 18. — Similar view of a specimen measuring 8x7 mm. 



Figure 18a. — Outline jjrofile of the same. 



Fkujre 1!*. — Similar view of a specimen measuring 21 X 20 mm. 



Figure l!)a. -Outline profile of the same. 



Figure 20. — Similar view of a full-grown specimen measuring 

 24 X 22 mm. 



Figure 2lla. — Outline prolile of tlie same. 



