NO. 2 DEICHMANN : HOLOTHURIOIDEA ; PART II, ASPIDOCHIROTA 321 



In the dark-colored material from Peru, the smallest specimens, 7 or 

 8 cm long, appear to lack all spicules except the end plates, but otherwise 

 they agree closely with the larger individuals taken in the same spot. 



11. Fossothuria n. gen. 

 (Holothuria rigida group) 



Diagnosis: Medium-sized forms, 6 to 15 cm long, with flattened 

 body with blunt ends and ventral mouth, surrounded by 20 small ten- 

 tacles, often completely withdrawn behind the sphincter; anus terminal. 

 Skin rigid from spicules. Ventrally small pedicels, completely retractile, 

 dorsally small papillae. Internal anatomy not remarkable. 



Spicules an external layer of tables with knobbed edge and low squat 

 spire with numerous blunt teeth gradually becoming connected with 

 projections from the margin of the disk, resulting in a reticulated hemi- 

 spherical mass. A crowded layer of regular knobbed buttons, dorsally 

 short with three pairs of holes, ventrally longer with 6 to 12 pairs of 

 holes; in older individuals some of the buttons becoming gradually almost 

 smooth. Ventral feet with end plate and flat supporting rods or plates 

 with few holes in the ends and along the sides of the central part. Dorsal 

 papillae without end plate or only a vestige, and similar rods or plates. 



Color white to gray or olive brown; outer pigment often partly 

 destroyed. 



Type species: Stichopus rigidus Selenka. 



Remarks: In this group belong the type species, which ranges from 

 the east coast of Africa to the Panamic region, and Holothuria cubana 

 Ludwig from the West Indies (including Selenka's West Indian ma- 

 terial of H. rigida and Deichmann's H. fossor). 



Fossothuria rigida (Selenka) formae typica, atypica 



PI. 8, figs. *-«• I - // 



Stichopus rigidus Selenka (partim), 1867, p. 317, pi. 18, figs. 30-31. 



Holothuria rigida, Deichmann, 1930, p. 56 (passim). Steinbeck & 

 Ricketts, 1941, p. 410. 



Holothuria fossor, Panning (partim), 1935, IV, p. 106, complete list of 

 references. 



Non Holothuria fossor Deichmann, 1926, p. 18, pi. 2, fig. 1 a-j (Fosso- 

 thuria cubana Ludwig) 



Cystipus pleuripus Haacke, 1880, p. 47. 



Holothuria pleuripus, Ludwig, 1883, p. 174. 



