English: Plate 27.

Fig. 1. Pseudechinus hesperus H. L. C. Holotype. x 8.

Fig. 2. Hesperaster arachnoides H. L. C. Holotype. Somewhat reduced. [= syn. of Ammotrophus arachnoides]

Fig. 3. Arachnoides tenuis H. L. C. Bare test of a paratype. Nat. size.

Fig. 4. The same. Oral view.

Fig. 5. Echinocyamus planissimus H. L. C. Bare test of large, broad paratype. x 4^1/2.

Fig. 6. The same. Oral view.

Fig. 7. Bare test of small, narrow paratype. x 4^1/2.

Fig. 8. The same. Oral view.

(In the colored plates, all figures are shown natural size, with the aboral or (in holothurians) dorsal side up, unless otherwise stated. Unless designated as young, the specimens were normal adults but in some cases small individuals were selected to save space. In the uncolored plates, the dorsal side is shown, but in some species the oral side is also presented. As a rule the holotype serves as the basis of the photograph. The magnification varies but is indicated in each case.)