ECHINODEEMATA. 157 



feet or ambulacra! tubes (CuviEn), or the union of both these 

 characters (BRANDT) into many genera. The arrangement of 

 BRANDT is circumstantial, and here and there rather artificial than 

 natural. Regard ought also to be had to the Habitus. If the 

 position of the Tentacles be made the chief point in the arrange- 

 ment, animals will be separated which in their habitus are nearly 

 allied. These tentacles are either branched like a tree, fingered, or 

 shield-like, (peltate), i. e. they consist of a pedicle with an expansion 

 which is disciform, often indented or arborescent. Their number is 

 usually ten, or twice ten. Where eight tentacles seem to be present, 

 sometimes on closer inspection two others, smaller and undeveloped, 

 are found, (the sub-genera Anaperus and Colochirus of TROSCHELL'). 

 In some no special internal respiratory organs are found (the genus 

 Oncilabes of BRANDT ; in most the arborescent respiratory organ 

 exists which we described above in Holothuria tubulosa. 



Pentacta GOLDF. (Cladodactyla, Dactylota, Oncinolabes, Aspido- 

 chir BRANDT). Feet equal, disposed in five, or, more rarely, in six 

 rows longitudinal, parallel. Body cylindrical or quinquelateral, 

 attenuated at both ends. Tentacles mostly ten, sometimes twelve 

 or fifteen. 



a) Tentacles peltate. 



Aspidochir BRANDT. A genus unknown to me. Sp. Aspidochir 

 Mertensii, in the island Sitcha (Tentacles 12). 



&) Tentacles ramose. 



Cladodactyla BEANDT (Tentacles 10). 



Sp. Pentacta Pentactes, Holoth. pentactes MUELL. Zool. dan. Tab. 31, fig. 8, 

 FORBES Brit. Starf. p. 213 ; Pentacta frondosa, Holoth. frondosa L., Holoth. 

 pentactes ABILDG. Zool. dan. Tab. 108, figs, i, 2, Tab. 124. FORB. Br. Starf. 

 p. 209 ; in the European seas. Pentacta doliolum, Actinia doliolum PALL. 

 Spic. Zool. Tab. XI. figs. 10 12. Cuv. JR. Anim. ed. ill. Zooph. PI. 20, 

 fig. 4. These species are called, from their external resemblance, Sea- 



c) Tentacles digitate or pinnate. 



Dactylota BRANDT. 

 Sp. Pentacta pellucida, Holoth. pellucida, Zool. dan. Tab. 135, fig. i. 



(Note. Here also is to be referred the genus Ocnus FORBES, Brit. Starf. 

 p. 229.) 



1 Neue Holothiirienyattunycn in ERICHSON'S Archiv f. Naturgesch. 1846, s. 

 6066. 



