THE APODOUS HOLOTHURIANS 123 



mark, or more commonly at depths of 10-220 m. It is especially remarkable 

 for its breeding habits. The eggs undergo their development in the genital 

 tubes of the mother, and consequently the species is not only viviparous but 

 is unique among holothurians in the possession of uteri. One cannot avoid the 

 feeling that a careful comparison of good material from Kerguelen and its 

 vicinity with material from the Strait of Magellan and the Falkland Islands 

 will show that there are two distinct species in these widely separated dis- 

 tricts. The specimens reported from the East Indies by Sluiter ( :01) prob- 

 ably represent a third species, while that from Hawaii (Fisher, :07) is very 

 likely a fourth; but of course it is not impossible that contortus does occur 

 throughout the southern hemisphere, and even extends its range northward into 

 the East Indies and among the Pacific islands. 



TROCHODOTA Ludwig, 18,2. 



Tentacles 10. Digits 2-6 on each side. Polian vessel single. Stone-canal 

 single. Calcareous ring of 10 slender pieces, the radial not pierced for pas- 

 sage of nerves. Gustatory organs sometimes (always?) present on tentacles. 

 Calcareous deposits consist of sigmoid bodies (Plates VII, figs. 2 and 6) (90- 

 160 /u. in length) either scattered irregularly through the skin or arranged in 

 circles or in little groups ; with these are associated wheels, like those of 

 Chiridota, but scattered through the skin and never collected in wheel-papillae. 



This is a very natural and well-defined group, first set off by Ludwig 

 ('926) under the name Trochodota. Its geographical distribution is remark- 

 able, for while one of the species occurs only at New Zealand, a second is found 

 only about the southern end of the American continent and the third is con- 

 fined to the Bay of Naples. The last is, however, such a small species and so 

 difficult to find that its range may really be very much greater than is sup- 

 posed. 



KEY TO THE SPECIES OF TROCHODOTA. 



A. Wheels about 150-180 /t in diameter; sigmoid bodies normally with one end rolled in- 

 ward, the other curved outward in a different plane, and neither end enlarged (plate 

 vii, fig. 6). 



Wheels scattered all over the body ; genital tube unbranched PURPUREA 



Wheels confined to 3 dorsal interradii; genital tubes somewhat branched. 



DUNEDINENSIS 



A A. Wheels about 80 p in diameter; sigmoid bodies not as above, often thickened at one 

 end (plate vii, fig. 3) VENUSTA 



TROCHODOTA PURPUREA. 



Ilolothuria (Fistnlaria) purpurea Lesson, 1830, p. 155; pi. 53, fig. 1. 



Chirodota purpurea Jager, 1833. 



Chiridota purpurea Brandt, 1835. 



Sigmodota purpurea Studer, 1876, p. 454 (partim). 



Chirodota australiana Theel, 1886a, p. 16. 



