NO. 2 DEICHMANN : HOLOTHURIOIDEA ; PART II, ASPIDOCHIROTA 297 



often some smaller marginal ones; spire low, with few teeth on top, 

 often partly resorbed. Inner layer either buttons, mostly irregular, in- 

 complete, often twisted, or in one species reduced to rods with lateral 

 lobes only rarely developing into complete buttons. 



Type species: Stichopus leucospilota Brandt. 



Remarks: In this genus have been placed a few of the members 

 of Panning's Abt. B, Reihe 1-3, and some of those referred to his Abt. 

 B, Reihe 8. One species from the latter division has turned out to be 

 identical with the type species, placed in his first division. At the present 

 moment, four species have been included in the genus, all exclusively 

 Indo-Pacific ; one is known only from American waters, while the 

 fourth, Mertensiothuria pervicax, extends as far eastward as Hawaii. 



Key to the species of the genus Mertensiothuria 



1. Spicules in inner layer small oblong rods with lateral projec- 

 tions resembling narrow rosettes, only rarely developed into 

 narrow buttons, mostly incomplete. Mottled. Indo-Pacific as 

 far eastward as Hawaii pervicax (Selenka) 



1. Spicules in inner layer buttons, complete or incomplete, rarely 

 regular 2 



2. Buttons mostly with two narrow holes and one to two smaller 

 pairs in the ends, holes often incomplete. Mottled, gray to 

 brown, paler below. Indo-Pacific, including Panamic region. 

 fuscocinerea (Jaeger) 



2. Buttons variously developed, from almost regular to twisted 



or irregular or incomplete 3 



3. Tables usually present, with low spire, ending in a flat circle 

 of 8 to 12 short, blunt teeth. Buttons delicate, mostly with 

 large holes, often narrow. Color faded, reddish or brown. 

 From the eastern coasts of Africa to the Panamic region. . . 

 leucospilota (Brandt) 



3. Tables usually reduced to four-holed disks, often totally lack- 

 ing. Buttons stout, mostly incomplete and with holes as a rule 

 round, not narrow. Color bluish black to brown dorsum and 

 pale, more grayish, ventrum. Juan Fernandez Island. 

 platei (Ludwig) 



Mertensiothuria leucospilota (Brandt) 



PI. 3, figs. 1-9 

 Stichopus leucospilota Brandt, 1835, p. 51. 



