305 



Polycheira Clark. 



Clark. 1908. The Apodous Holothurians. pag. 129. 



Genotype: Chiridota rufescens Brandt (= Ch. variabilis Semper). 



The genus Polycheira was established in 1908 by Clark for 

 the 18-tentacled species, hitherto referred to Chiridota. That the 

 number of tentacles really indicates a generic difference is sup- 

 ported by the character of the ciliated funnels. These are in Poly- 

 cheira always united into stalked clusters, which may be rather 

 large, ca. 1 mm, though the funnels themselves are small. The 

 new species P. echinata differs in the shape of the clusters some- 

 what from the other species, as the clusters in this species are 

 unusually small and very like those of the funnels in Ch. hawaii- 

 ensis Fisher, but they differ from hawaiiensis in their arrangement. 

 In hawaiiensis the ciliated funnels are united into clusters only close 

 to the base of the mesenteries, and single funnels are always found. 

 In P. echinata the clusters of funnels are more equally spread over the 

 mesenteries, and all the funnels are united into clusters. Clark 

 has established the genus as a monotypic one, as he supposes that 

 all the different species described with 16 — 19 tentacles are really 

 the same species, rufescens Brandt. With this I cannot agree, and at 

 any rate I think that Semper's two species variabilis and vitiensis 

 are different. The differences in the calcareous deposits are ac- 

 cording to Semper rather slight, and at any rate not very reliable, 

 as the deposits in variabilis are so variable; but the figure of the 

 ciliated funnels makes it clear that the two species are not syn- 

 onymous. The funnels are in variabilis ca. 100 long and in 

 vitiensis ca. 350 fi long. The large collection of variabilis at hand 

 shows no distinct variation in the size of the funnels, though the 

 size of the clusters may be much varying, which indicates that it 

 must be erronous to refer vitiensis to variabilis. 



Besides the specimens of variabilis, Dr. M orten sen's collection 

 includes a single specimen of another species of Polycheira. It is 

 described below under the name echinata, in reference to the peculiar 

 spinous rods, which distinguish it from variabilis. This single spec- 

 imen is obviously a very young one and for that reason it does not 

 contribute much to the classification of the genus. Only it may be 

 said that it is almost certain that the species and specimens which 

 are referred to rufescens Brandt by Clark and Ohshima will prove 



Vidensk. Medd. fra Dansk naturh. Foren. Bd. 85. 20 



