THE APODOUS HOLOTHURIANS 



13 



ber treated is 118, of which 2(5 are regarded as of doubtful standing. The 

 classic work of Ludwig ('92fc) in Bronn's Thierreich introduces an entirely 

 new basis of classification and breaks up the suborder Apoda. Ludwig shows 

 that the embryology of the Syjiaptidge sets them apart as a distinct group from 

 the other holothurians, and he therefore divides the class Hoi.OTHUBiomEA into 

 two orders, the Actinopoda and the Paractikopoda, distinguished by the place 

 of origin of the circumoral tentacles. The Actinopoda include four families, of 

 which the last is the Molpadiidiv, containing the footless species. The Paracti- 

 nopoda includes the single family Synapiida. Ludwig's arrangement of 

 genera is as follows : 



Moli.a.liidie = Moli.adia (2 species), Eupyrgus (l),!Haplodactyla (5), Caii.liiia (4), -I'l-ochostoma 

 (12), Ankyroderiua (8). 



6 genera, 32 species. 



Synapti.l* = Synapta (51 s(.ecies), Anapta (5), Chiridota (20), Trochodota (2), Tn.cliodenua 

 (1), Myriotrochus (1), Acantliotroclnis (1). 



7 genera, 81 si)ecies. 

 Total, 13 genera, 113 species. 



The last important paper of the nineteenth century dealing with the classi- 

 fication of the footless holothurians is Ostergren's ('985) admirable revision 

 of the Synaptid.T. He proposes to divide the family into three subfamilies, 

 chiefly because of differences in the calcareous deposits: Synaptinae with 

 anchors and plates, or occasionally (Anapta) only miliary granules; Chirido- 

 tins with 6-spoked wheels, or sigmoid or bracket-shaped particles, never anchors; 

 Myriotrochin* with wheels having 8 or more spokes, never collected in papilla?. 

 Under the Svnaptina^, he places Anapta and five other genera, made from the 

 old genus Synapta, as follows : Euapta, Chondrocloea, Synapta, Labidoplax, 

 Protankyra. These genera are distinguished from each other mainly by the 

 shape of the tentacles and anchors and anchor-plates. Under the Chiridotin-s 

 are placed two genera, Sigmodota and Chiridota, while Myriotrochus, Trocho- 

 derma, and Acanthotrochus make up the third subfamily. Altogether Oster- 

 gren recognizes 81 species of Synaptida^, the same number listed by Ludwig six 



vears before. 



The report on the holothurians of the "Travailleur" and "Talisman, by 

 Remy Perrier (:0:3), returns to the old arrangement of Brandt again, but is 

 notable for the relative rank given previously recognized groups. He con- 

 siders the apodous holothurians a natural assemblage, and ranks them as a 

 subclass, the Apodes. This subclass includes two orders, the Anactinopod..^ 

 with one family, the Molpadiids, and the PARACTI^^opoDA with three families, the 

 Svnaptida^, Chirodotidi^, and Myriotrochida>. Thus Ostergren's subfamilies are 

 here raised to full familv rank. Delage and Herouard ( :04) recogmze two 

 orders, AcTiNOPODiDA^^^ndJWmNO^^ 



rsp^lkZ^;^^^^ on p.f.e. -m. where fir.t iiitroduced ; elsewhere spelled as above given. 



