236 PROCEEDINGS OP THE AMERICAN ACADEMY 



females. See PI. IV., Figs. 4-8, Echini of Hassler Exiiedition. 111. 

 Cat. Mus. Comp. Zool. No. VIII. I have examined a large number 

 of a common Spatangoid from our southern coasts (INIoira atropos), 

 with ambulacra still more deeply sunken than in Hemiaster, in hopes of 

 finding the young, but thus far without success ; from the eggs of Schi- 

 zaster canaliferus from the Mediterranean, in which some of the am- 

 bulacra are also deeply sunken, a pelasgic Pluteus is known to be 

 developed ; so that in many of the genera with sunken ambulacral 

 petals the sunken area does not shelter the young in their earliest 

 stages of development. 



