i XOGASTRl I \lloN AND RELATED MODIFICATION-. JI 



by lithium treatment, deviating from the normal in the -aim- 

 nd ( --entially to the same degrees as do the sand-dollar 

 lithium larva-. The concentrations required are rather higher, 

 the mo-t numerous and typical lithium effects being indiuvd in 

 the Atlantic species by about X 80 to X 100 LiCl, and in the 



fie I'orm by X 100 or less. 



Several hundred sketches of teratological types in these 

 un hins (the very common types seen in Figs. 6, 7) conform so 



Fit.. 7. Modified > ' M joo; /-/. 



from LiCl. M 150; m-o, from NaCl. M i M..MI K N MO; r-z, from 



CaCI?. M/ifto to M/2OO. 



closely to the sand dollar fonn> just dc-i -rilu-il .Mid to the modifi- 

 cations illustrated and described -in >m-h -real detail by Herbst 

 Ti)- 1 . 'i)5<;. '956) for Echinus nii<rotul>cr(it!<itns, SpharechinuS 



