bo 
Piate 57. 
1-5. Pourtalesia Tanneri A. Ag.; Station 3431. 
Actinal part of the odd interambulacrum and _ parts of test surrounding the 
actinostome of a specimen 16 mm. in length. 
The odd anterior ambulacrum and parts of test adjoining actinostome, seen from the 
interior, the same specimen as fig. 1. 
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. 
The plates of the odd interambulacrum surrounding the anal opening, the same as fig. 1. 
Development of the plates of the test surrounding the actinostome, the same as fig. 1. 
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