80 THE APODOTJS HOLOTHUEIANS 



SYNAPTULA Oersted, 1849. 



Hcierosynapta Verrill, 1867. 

 Chondroclcea Ostergren, 1898 (partim). 



Tentacles pinnate, 10-15. Digits at least five on each side. Cartilaginous 

 ring present. Polian vessels three or more. Stone-canal single, unbranched. 

 Sense-organs in form of pigment-eyes at the base of tentacles on oral disc, 

 often (always?) present. Stock of anchors finely toothed, but not branched; 

 arms smooth, but vertex with a few minute knobs. Anchor-plates with a large 

 central hole surrounded by six other large holes, all more or less dentate, and 

 with two large and several small smooth holes at the narrow, posterior end, 

 where a well -formed and distinctly arched bow crosses outer surface of plate. 



This genus contains an unusually large number of poorly described or im- 

 perfectly known species, so that it is exceedingly difficult to determine which 

 are valid. Those which are well known occur upon or among seaweeds and 

 corals, creeping about very slowly by means of their tentacles and the worm- 

 like movements of their bodies, clinging tenaciously to a rough surface by 

 their anchors, and feeding upon diatoms and other micro-organisms. All the 

 known members of the genus are tropical. It is almost certain that some of 

 the oriental species here given as valid are really identical with some of the 

 others, but further and more careful study of plentiful material is necessary 

 to determine their true relationships. Whether Chiridota verrucosa and lum- 

 bricoides (Synapta lumbricus Jager ('33) ) of Eschscholtz ('29) and Fistularia 

 reciprocals (Holothuria glutinosa Lamarck ('16)) and vittata of Forskal 

 (1775) really belong .to this genus it is simply impossible to say from the avail- 

 able evidence. The Synaptid which Herouard ('93) identified as reciprocans 

 is almost certainly Synaptula nigra; but, as Forskal 's description is practi- 

 cally worthless, it is impossible to determine whether Herouard and he refer to 

 the same animal. As for vittata, Miiller ('54), Lampert ('85), Ludwig ('866), 

 Bedford ('99a), and Sluiter ( :01) all profess to have found it, but none of 

 them give any distinguishing characters or add anything to Forskal 's (1775) 

 original inadequate description. Their remarks are not altogether consistent, 

 and it is hard even to determine the genus to which the species should be 

 referred. The figures given by Held ('57) show clearly that his specimen was 

 an Euapta. The name had better be entirely discarded and with it, of course, 

 Leuckart's genus Tiedemannia, of which it is the type. Since Oersted ('49) 

 made Synapta vivipara (=H. hydriformis Le Sueur) the type of a new genus 

 Synaptula, it is clear that this name should have precedence over Ostergren 's 

 (1898) name Chondrocloaa, for Ostergren places Oersted's vivipara in his later 

 genus. It seems probable, however, that, as at present constituted, Synaptula 

 includes at least two groups of species which further knowledge will necessi- 

 tate recognizing as separate genera; one of these is best represented by nigra 



