100 THE APODOU8 HOLOTHUEIANS 



Anchor-arms with 5 or 6 teeth and holes in plates with 



1-3 teeth or none BENEDENI 



00. Anchors over 1 mm. long. 



Plate abruptly contracted posteriorly and provided with 

 very numerous, small, entire holes (plate v, fig. 33). 



RODEA 

 Plate not abruptly contracted; provided with holes of 



very unequal size DENTICULATA 



CC. Anchors conspicuously asymmetrical (plate iv, fig. 15; plate v, fig. 36). 

 D. Accessory calcareous bodies in the form of perforated plates. 



Accessory perforated plates normally with 4 dentate holes (plate v, 



fig. 35) ASYMMETRICA 



Accessory perforated plates normally with 10 dentate holes (plate v, 



fig. 34) LUDWIGII 



DD. Accessory calcareous bodies in the form of small cruciform or branched 

 rods (plate iv, fig. 16). Anchors grotesquely asymmetrical (fig. 15). 



PETERSI 



BB. Anchors and plates of two distinct sorts, differing especially in size; large anchors 

 with serrate arms. 



Large anchor-plates with comparatively few (less than 100) holes; these are 

 rather large, polygonal, and smooth; small anchors with smooth arms; ac- 

 cessory calcareous bodies, small cruciform or branched rods. 



PSEUDO-DIGITATA 



Large anchor-plates with numerous (150 or more) holes; these are small, cir- 

 cular, and dentate; small anchors with serrate arms; accessory calcareous 



bodies, minute oval granules BANKENSIS 



AA. Tentacles 10; brackish water SIMILIS 



PROTANKYRA CHALLENGERI. 

 PLATE V, FIG. 26. 



Synapta challengeri Theel, 1886a, p. 14. Calcareous particles, pi. i, fig. 4. 

 Protankyra challengeri Ostergren, 1898&. 



Protankyra challengeri var. Sibogm Sluiter, 1901, p. 131 ; pi. in, fig. 5. 

 ProtanJcyra timida Koehler and Vaney, 1905, p. 108. Calcareous particles, pi. xv, 



figs. 33-35. 

 Protankyra albatrossi Fisher, 1907, p. 728. Calcareous particles, pi. LXXXI, figs. 1. 



la, and pi. LXXXII, figs. 4, 4a-c. 



LENGTH. 80-100 mm. 



COLOR. Beddish, yellowish or whitish, sometimes with a lilac tinge. 



DISTRIBUTION. Reported from near the Fiji Islands, 252 m. (Theel) ; from 

 near Aru, Arafura Sea, 1,788 m. (Sluiter) ; near Andaman Islands, 1,010 and 1,170 

 m. (Koehler and Vaney) ; Hawaiian Islands, 257-1,586 m. (Fisher). 



REMARKS. The anchor-plates ally this species to the preceding genus, 

 with which it is a sort of connecting link. Sluiter 's specimens were so nearly 

 like Theel 's that the slight differences in color, anchor-plates, and abundance of 

 miliary granules are not enough to warrant our regarding the form as a dis- 

 tinct variety; neither is the difference in the depths at which they were taken 



