Plate 57, 

 1-5. Pourtalesia Tanneri A. Ag. ; Station 3431. 



1. Actinal part of the odd iuterainbulacrum and parts of test surrounding the 



actinostome of a specimen IG nun. in length. 



2. The odd anterior ambulacrum and parts of test adjoining actinostome, seen from the 



interior, the same specimen as fig. 1. 



3. Actinal parts of the odd posterior interambulacrum and adjoining parts of the test, 



seen from the interior facing the opening of the actinostome, the same as fig. 1. 



4. The plates of the odd interambulacrum surrounding the anal opening, the same as tig.l. 



5. Development of the plates of tlie test surrounding the actinostome, the same as fig. 1. 





