16 THE APODOUS HOLOTHURIANS 



of the genus Synaptula by Oersted in 1849, and they must therefore be called 

 by the earlier name, of which Chondroclcea is obviously a synonym. One spe- 

 cies of this group, however (kefersteinii), is so distinct from the others in its 

 large number of tentacles that it may well be considered as the representative 

 of another genus, for which I would suggest the name Polyplectana (see page 

 76). Ostergren's other genera Anapta, Euapta, Labidoplax, and Protankyra 

 are all valid and may be accepted without further discussion. His genus 

 Synapta, however, must bear the name Leptosynapta, proposed for it by Ver- 

 rill in 1867. 1 To these genera it is now necessary to add the recently redis- 

 covered Ehabdomolgus Keferstein. It is also necessary to recognize a new 

 genus, Dactylapta (see page 111), for a remarkable species from the Indian 

 Ocean. Fisher's ( :07) division of Euapta into two genera seems to me of 

 doubtful value, but the two groups are as easy to distinguish from each other 

 as they are from Synaptula, and we may therefore recognize Opheodesoma, for 

 the present at least, without doing violence to any natural relationships. We 

 thus recognize 11 genera of Synaptinre. 



When we come to the Chiridotinae we must first of all determine to what 

 characters we will give the most weight. The number of tentacles offers an 

 obvious and tempting character, but one which must be used guardedly; it does 

 not seem to be natural or justifiable to separate forms with 10 tentacles from 

 those with 12, solely on that ground. Of course, where the difference in num- 

 ber is greater, the character has more weight. It is probable that Ludwig is 

 right in putting the emphasis on the distribution of the calcareous wheels, 

 while the presence or absence of the sigmoid bodies may be regarded as the 

 feature of second importance. With these principles in mind, we find the classi- 

 fication of this subfamily quite simple. Ostergren divides it into two genera, 

 Sigmodota and Chiridota. The former genus was suggested by Studer ('76) 

 for species having calcareous particles in the form of sigmoid bodies. Oster- 

 gren proposes to include in Sigmodota all the species with sigmoid bodies, 

 whether they have wheels or not, restricting Chiridota to species having no 

 sigmoid bodies, and with the wheels in papilla?. The genera Toxodora Verrill 

 ('82) and Trochodota Ludwig ('92&) are thus included in Sigmodota by Oster- 

 gren, though he recognizes three distinct groups in the genus. Ludwig (92fe) 

 puts Toxodora under Anapta and bases Trochodota on the species with 10 ten- 

 tacles, the wheels scattered (i. e., not in papillae), and sigmoid bodies present. 

 The tentacles of Toxodora, however, are peltato-digitate, whereas those of 

 Anapta are pinnate; the calcareous particles are also of essentially different 

 types; it is hardly legitimate, therefore, to unite the two groups, for 

 there is no reason to believe that they have a common ancestry or any close 

 genetic connection. Verrill 's genus appears to be valid and may be defined as 



1 Fisher (:07) has already called attention to these necessary modifications of Ostergren's names. 



