THE APODOUS HOLOTHURIANS 181 



of Grube's name, which was really a synonym of Cnvier's genus Molpadia. As 

 Semper 's mistake has not hitherto been corrected, it is now necessary to give 

 the genus a new name. Geographically, Aphelodactyla is interesting because of 

 its very limited distribution. Although nine species or varieties have been 

 named, they are all from the East Indian region, extending only to Ceylon on 

 the west and to Waigiou Island, near New Guinea, on the southeast ; curiously 

 enough, the same species occurs at these two extremes. All are shallow-water 

 forms, occurring from about low-water mark to only about 60 m. The species 

 are all imperfectly known and it would not be surprising if future study of 

 sufficient material should show that there are only two, or perhaps three, distinct 

 species in the genus. 



Key to the Species of Aphelodactyla. 



A. — Skin more or less opaque and jiigmented. 



B. — Calcareous particles sometimes wiinting, sometimes present only near cloacal open- 

 ing, sometimes frequent, especially posteriorly, in the form of small oval bodies, 

 and more or less irregular, perforated plates (plate x, figs. 4, 5). 



Color uniform reddish violet or purplish; plates wlien present ratlier regidar, 



thick, with few small perforations molpadioides 



Color clear violet, marked with orange; plates when present very irregular, 



sometimes with numerous perforations punctata 



BB. — Calcareous particles small, oval, or thick C-sliaped, or dumbbell-shaped, bodies. 



australis 

 A A. — Skin more or less glassy and transparent, sometimes without pigment. 



Calcareous particles wliolly wanting pellucida 



Calcareous rods with projecting knobs present near cloacal opening hyaloeides 



Aphelodactyla molpadioides. 

 Plates III and X, Figs. 3-7. 



Ilaplodacti/la molpadioides Semper, 18(38, p. 41 ; pis. ix; x, figs. 2a, 4, 5, 9 ; pi. xiii, 



1-3. 

 Haplodactyla molpadioides sinensis Semper, 1868, p. 43. Calcareous particles, pi. x, 



fig. 2 ; pi. XIII. fig. 4. 

 Haplodactyla ecalcarea Sluiter, 1901, p. 118. 



Length. — Up to 210 mm., with a diameter about one-fourth as much. 



Color. — Uniform reddish violet or purplish. 



Distribution.— Reported from Bohol and Cebu, Philippines (Semper) ; 

 China (Semper); Sumbawa. D. E. I. (Sluiter), and Ceylon (Bell). 



Remarks.— Although so beautifully iigured and well described by Semper, 

 this species is still very unsatisfactorily known. Few sjiecimens are in collec- 

 tions and its relationships to other members of the genus are still much in doubt. 

 The single small specimen (35 mm.) taken by the "Siboga," and which Sluiter 

 named ecalcarea, seems to be most probably a young individual of this species. 



