Explanation of Plate I. 



Actinometra iowensis, n. sp. 



Fig. 1. Dorsal view of specimen Natural size 



Fig. 2. Ventral view of another specimen, from which one 

 ray has heen removed, so that the cirri show 

 through at that side. This shows the disk-ambu- 

 lacra, central anal tube, marginal mouth, and 

 plated ambulacra in the arms; also in some places 



the combed pinnules Natural size 



Fig. 3. Ventral view of lower part of an arm, showing the 



covering plates of the ambulacrum x2. 2 



The above three figures are from photographs direct from the speci- 

 mens, and may be advantageously studied with a low power magnifier, 

 such as an ordinary reading glass. The following figures, 4, 5, and 6, 

 are from drawings. 

 Fig. 4. Ventral side of arm at median part, showing the 



covering plates of the ambulacrum X6 



Fig. 5. Ventral side of a pinnule from distal portion of arm, 



showing the covering plates ,., xlO 



Fig. 6. Terminal comb of proximal pinnule XlO 



