NO. 3 DEICHMANN: HOLOTHURIOIDEA ; PART I, DENDROCHIROTA 99 



valves. Tentacles 10, the 2 ventral smaller. Skin rigid, filled with spicules. 

 Calcareous ring simple, posteriorly often strongly undulated but never 

 with posterior prolongations. 



Spicules consisting of an external layer of either baskets or delicate 

 reticulated bodies, and inner layer of knobbed buttons, heavy plates, or 

 reticulated bodies. Feet apparently with no end plate; walls supported 

 by perforated rods or plates; dorsal papillae with mostly curved sup- 

 porting plates. Tropical shallow water forms. 



Type species. — Pentacta doliolum (Pallas). 



Remarks. — The name has been used by various authors for members 

 of the genus Cucumaria s.l., and Ludwig (1899, p. 344) claims that it 

 ought to be used instead of Blainville's name, from 1835. H. L. Clark 

 (1923, p. 416) has, however, called attention to the fact that Troschel's 

 name Colochirus is a complete synonym of Pentacta, for Goldfuss desig- 

 nated Pallas' doliolum from Cape of Good Hope as the type species and 

 the latter is generally accepted as the typical "Colochirus." 



The genus Pentacta is most abundantly represented in shallow water 

 in the East Indies. The type species represents the only form known from 

 the South African waters, and only one form is known from Brazil and 

 the West Indies. From the western coast of South America Semper de- 

 scribed a new species which was never found again and hence was re- 

 garded as rather dubious. There is no doubt that it is the one which the 

 Allan Hancock Expeditions now have brought back, thereby proving 

 that Semper's specimens were correctly labeled. 



The genus may possibly in the future be divided into 2, viz., one for 

 those with more complicated spicules, and one for those with regular, 

 knobbed buttons and simple baskets. 



The 2 species known from the American waters both belong to the 

 latter group. 



Pentacta peruana (Semper) 

 Plate 16, Figs. 1-8 



Colochirus peruanus Semper, 1868, p. 239, pi. 39, fig. 20. — Lampert, 

 1885, p. 126.— Theel, 1886, p. 123.— H. L. Clark, 1910, p. 353. 

 Diagnosis. — Small form, few cm. long, with cylindrical feet in 3 

 crowded bands on the greater part of the ventral side, transformed into 

 papillae toward the ends, dorsally 2 bands of papillae and a number 

 scattered in the interambulacra. Oral and anal ends closed by 5 distinct 

 valves. Inner anatomy typical of the genus. 



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