NO. 3 deichmann: holothurioidea; parti, dendrochirota 93 



Type species. — L. grisea H. L. Clark, 1938. 



Remarks. — The genus may possibly be further divided into two, viz., 

 Leptopentacta, which includes the type species, L. panamica spec, 

 nov., possibly also Sluiter's "Ocnus" javanicus, and a species listed here as 

 L. nina, based on a juvenile individual from the Hancock Expeditions, — 

 and another, for which the name Parocnus is proposed, — to accommodate 

 "Ocnus" imbricatus Semper and "Ocnus" typicus Theel, which possibly 

 are identical, and L. nova, spec. nov. 



1 



Text fig. 2. 



1. Calcareous ring from Leptopentacta grisea H. L. 

 Clark. 



2. Leptopentacta panamica, new species. 



3. Leptopentacta javanica (Sluiter). 



Scale, 1 mm.; Sluiter's figure has no indication of 

 what magnification is used; probably it is about as 

 large as the other two. 



"Ocnus" molpadioides Semper definitely does not belong in this genus, 

 while "Ocnus" pygmaeus Semper, based upon a specimen 1 cm. long, has 

 long and rather flexible feet and probably represents a juvenile specimen 

 of some species of Cucumaria or Thy one (in the broad sense). It is not 

 possible to ascertain whether the calcareous ring is simple or has pos- 

 terior prolongations. Semper figures a simple ring but mentions that the 

 ring has long posterior prolongations. His figures of the ring of imbricata 

 show no posterior prolongations, and in his description he emphasizes the 

 way in which the ring is cut off posteriorly. (See footnote, p. 94.) 



Key to the Known Species of Leptopentacta 



1. External layer of spicules consisting of small biscuit-shaped 

 plates or rosettes. Feet with no supporting rods, and apparently 

 without end plate. Calcareous ring simple (not known in L. 

 typica) 



