314 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 11 



Panning's record of Ludwigothuria atra from the Galapagos refers 

 undoubtedly to Clark's record from Clipperton Island, which Clark had 

 mentioned in his Galapagos report. However, as L. atra is rather com- 

 mon in the Galapagos Islands, his statement stands. The first record of 

 L. atra in the Panamic region is Clark's 1902 listing of 9 specimens 

 from Clipperton Island. 



10. Selenkothuria n, gen. 

 (Holothuria lubrica group) 



For literature, see Panning, 1934, II, pp. 45-48, text-figs. 38-42. 



Diagnosis: Soft-skinned forms with numerous cylindrical feet, 

 forming a more or less distinct ventral sole, sometimes arranged in three 

 broad bands ; dorsally numerous minute papillae, not conspicuous, rarely 

 forming low warts. Tentacles more or less terminal in position, often 

 bushy, adapted for plankton catching (?). Inner anatomy not remark- 

 able; certain species with numerous stone canals, others with a single 

 large one; usually one Polian vesicle; gonads as divided threads in a 

 tuft behind the low calcareous ring; Cuvierian organs present in all 

 forms. 



An external layer of tables usually completely lacking, though 

 vestiges of tables sometimes found in young individuals of certain species. 

 The inner layer consisting of small rods or plates, smooth or spinous. 

 Ventral feet with large end plate and walls supported by rods or plates 

 of same size as those in the skin, rarely special supporting rods present. 

 Dorsal appendages with reduced end plate or none, and often more 

 curved, shorter rods. 



Color dull gray with or without two rows of dark spots and darker 

 anterior end, or dark brown to black. 



Type species: Holothuria lubrica Selenka. 



Remarks: Although Panning's group is correctly interpreted, he 

 has unfortunately been so loaded down with most of the errors made by 

 earlier writers that many of his conclusions about distribution are com- 

 pletely misleading. Thus his figures of Holothuria lubrica var. glaber- 

 rima represent H. erinaceus Semper {=^H. marenzelleri Ludwig), 

 entirely different from Selenka's H. glaberrima, from the West Indies; 

 while the Indo-West Pacific material of H. lubrica var. lubrica de- 

 finitely must be referred to H. moebi, Ludwig, and so forth. 



In order to clarify the situation a key is given to all the accepted 

 species with their approximate geographic distribution. 



