162 THE ECHINODERMS OF TORRES STRAIT. 
but of many higher animals, where, if we choose to ignore details and overlook slight dif- 
ferences, all the species can be united under a single specific name, with disastrous results 
to the study of the evolution of species and their distribution. 
Comparison of the present Torres Strait Leptosynapta with the Australian species 
shows at once that its anchors and plates are only about two-thirds as large as those of 
dolabrifera, while the anchors have a different form, the vertex being more curved and the 
arms longer, more slender, and more nearly parallel with the shaft. (Compare figs. 12a 
and 13, pl. 36.) There are differences in the plates, too, the most noticeable being that in 
latipatina the bridge seems to be less fused with the plate. The miliary granules are much 
alike in the two species and quite different from those of inhwrens. I have no doubt that 
good material showing tentacles, calcareous ring, etec., will show that the recognition of 
latipatina as distinct from both inherens and dolabrifera is amply justified. 
Protankyra similis. 
Synapta similis Semper. 1868. Holothurien, p. 10, pl. iii, fig. 2; pl. iv, fig. 14. 
Protankyra similis Ostergren. 1898. Ofv. K. Vet.-Akad. Forh., 66, p. 117. 
This Philippine species is included here on the strength of a headless fragment taken 
by Semon near Thursday Island, which Sluiter (1894) decided from the calcareous parti- 
cles belongs to similis. This species is otherwise not known from outside the Philippines. 
It is important to note that Semper seems to have made a mistake in giving 10 as the 
number of tentacles, for the cotype in the Museum of Comparative Zodlogy, received 
from him, and a second specimen, apparently of the same lot, have 12 tentacles each. 
This necessitates a change in my key to the genus (1908), as similis is there set off by itself 
as the only Protankyra with 10 tentacles. It really belongs in the section of the key with 
insolens and benedeni, but is distinguishable from those species at once by the accessory 
calcareous particles, which are short straight rods, forked at each end, an unusual and very 
characteristic form. 
Protankyra verrilli. 
Synapta verrilli Théel. 1886. Challenger Hol., p. 12, pl. i, fig. 1. 
Protankyra verrilli Ostergren. 1898. Ofv. K. Vet.-Akad. Forh., 56, p. 117. 
The two specimens on which this species is based were taken by the Challenger near 
Cape York in 8 fathoms. So far as I know, it has not been met with since. 
Chiridota rigida. 
Semper. 1868. Holothurien, p. 18, pl. iii, fig. 3; pl. v, figs. 3, 13. 
This widespread representative of a perplexing genus was originally described from 
the Philippines. What seems to be the same thing occurs at various points in the East 
Indies, at Rotuma, at the Hawaiian Islands, at the eastern end of New Guinea, and at 
the Murray Islands. The single specimen we found at Mer was discovered by my col- 
league, F. A. Potts, while he was digging for worms among the eel-grass roots in the sandy 
mud of the northwestern reef-flat. It is a small individual, less than 40 mm. long in life, 
pale reddish, with few, scattered wheel papilla. The habitat of this specimen was so unlike 
that whence Semper’s and Fisher’s specimens were taken (soft, sandy bottom of tide-pools 
on coral reefs) that I thought it might prove to be something distinct from rigida, but I 
have not found any way by which it can be distinguished from Philippine or Hawaiian 
material of the same size. In the Philippines, rigida grows to a considerable size; some 
specimens in the Museum of Comparative Zodlogy, from Bantayan Reef, Cebu, must have 
been 125 mm. long, and possibly more, in life. 
