320 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 11 



middle of the bar, and the edges sometimes finely spinulated ; occasional- 

 ly a third arm developed on the bars. Feet with end plate and a varying 

 number of rods or plates, usually more delicate than those in the skin. 

 Dorsal appendages M^ith small end plate or none, and a few rods or 

 plates. The spicules varying in length, from 0.06 to 0.22 mm, and be- 

 coming larger and more complex with age. 



Color varying shades of brown and gray, occasionally almost black. 



Type: Biol. Inst. U.N.A.M., Mexico. 



Type locality: Puerto Vallarte, Jalisco, Mexico (20° 30' N, 105° 

 15' W) 



Distribution: The Velero III material has shown that this species 

 is extremely common in the Galapagos Islands, where the material came 

 from that Deichmann figured in 1938 as "possibly" being the aged stage 

 of Holothuria marenzelleri var. theeli. Along the mainland it ranges 

 from Zorritos, Peru, Manta Bay, Ecuador, Octavia Bay, Colombia, 

 Salinas Bay, Costa Rica, Panama, to Tangola Tangola, Cape San Lucas 

 and Puerto Vallarte. Except at the last locality, only a few specimens 

 were collected in one place. 



Depth: All the material appears to have been collected at low tide 

 level. 



Specimens examined: A few large individuals from the Galapagos 

 (Arcturus) and 49 specimens from 17 Velero stations. In addition, one 

 individual from Panama was found in Selenka's type material of Holo- 

 thuria languens. 



Remarks: The Velero material proved definitely that this species 

 could not be the aged stage of Selenkothuria theeli, as suggested in 1938. 

 The material ranges in size from 2 to 15 cm and the largest specimens 

 must measure at least 20 cm when expanded. 



In a recent paper (1954) Dr. Caso has devoted several pages and 

 numerous illustrations to this species, of which she had 50 specimens 

 from the type locality, ranging in size from 6.8 to 11.3 cm. Her measure- 

 ments agree with those of the Velero material except that she has not 

 found quite as large spicules in her comparatively small specimens. Very 

 likely her locality and Cape San Lucas represent the northernmost limit 

 for the species, and it may not reach the size there that it does in the 

 Galapagos Islands. 



Judging from the literature, the species stands rather isolated, with- 

 out any parallel form in the Indo-West Pacific. Small faded specimens 

 may be mistaken for Selenkothuria lubrica, which usually occurs in the 

 same localities, though rare in the Galapagos waters. 



