290 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 11 



acteristic of M. parvula also occurs in M. difflcilis is not known, as all 

 the Pacific material has been so well cared for with fresh alcohol that 

 no trace remains in the material I have seen. 



The species is common both in Hawaii and in Easter Island, and 

 from the abundance with which it occurs in the Hancock collections one 

 seems justified in considering it a permanent element in the Panamic 

 region. 



Clark's Holothuria frequentiamensis, from Clipperton Island, was 

 previously withdrawn as a synonym of Microthele difflcilis and the same 

 fate must befall Deichmann's Actinopyga bedfordi, based on some young 

 specimens from Funafuti and Rotuma, identified as Holothuria parvula 

 by Bedford. Clark's Holothuria altimensis, from Thursday Island, has 

 also proved to be a young Microthele difflcilis in which a few "synal- 

 lactid" tables with cross-shaped disk were preserved — a feature which, 

 as the Hancock material has shown, may exist also in other species. 



3. Brandtothuria n. gen. 

 (Holothuria arenicola group) 



Diagnosis: Comparatively slender, spindle- or bottle-shaped forms, 

 of moderate size, rarely 25 cm long, with 20 small terminal tentacles 

 and terminal anus. Appendages not numerous, more papilliform on the 

 dorsum, and often distinctly arranged in five bands. Inner anatomy not 

 remarkable except in Brandtothuria arenicola (ring canal placed some 

 distance behind the calcareous ring) ; usually one stone canal and one 

 or two Polian vesicles; Cuvierian organs present, variously developed. 



Spicules an external layer of tables with smooth edged disk and, in 

 the adult, a low spire with a varying number of teeth; in young indi- 

 viduals, the spire sometimes tall with several crossbeams. Inner layer of 

 smooth buttons of moderate size, usually with three pairs of holes. Ven- 

 tral feet with large end plate and supporting rods or plates, dorsally 

 small end plate or none, and supporting rods more narrow and often 

 curved. Usually concealed among rocks or buried in sand or mud. 



Type species: Holothuria arenicola Semper. 



Remarks: At the present moment the genus is restricted to three 

 species, all included by Panning in "Sporadipus" without making it clear 

 what characterizes that group. It seems to be a large motley array of 

 mostly unrelated forms. Brandt used the name for two species, S. 

 ualanensis and S. maculatus, which cannot be identified, although many 

 think that the last named, from Bonin Island, may be the same form 



