ArTixoroDors iioLOxnurjoinEv. 



41 



The animal in life clothes itself with sand grains, small shells 

 and shell fragments, which adhere In- action of its numerous 



pedicels. 



With the exception of 

 endplates which are found 

 on the ends of the small 

 dorsal, the large lateral and 

 small ventral pedicels, there 

 is only one kind of calcare- 

 ous deposit, viz., the tables 

 {h — ('). In the ventral, pcri- 

 some, the tallies measure 

 Textfig. 9. from 0.07 to 0.10 mm. in 



Mesothuria itenni: a-Calctvreous ring; b, r- diam., and their SpirO 0.05 



Tiibl&s of ventral perisome ; d, e — Same o£ pedi- 

 cel. ('■— 6x225). I— laterradialin ; R— Kailialia. UlUl. in height. SpirO 



consists almost always of three pillars. It has generally only one 

 crossbeam. The crown has several teeth on the top of each of the 

 three pillars. Xo elongated diverging ends to the pillars as in 

 some species. Tables on the pedicels not difi'erent in shape, l)ut 

 smaller in size, the disks measuring 0.05 — 0.07 mm. in dianreter. 

 No supporting rods. 



Remarks : — The fact that these specimens are without any 

 tentacular ampullae and that tlieir two-branched respiratoiy tree 

 does not intermingle with tlie blood vessels of the alimentary 

 tract, at once puts them in the su];)-family Synallactinae ; and the 

 presence of only one genital l)undk' on the left side makes them 

 reforrable to the genus Mesothuria. Even in the narrowed definition 

 of the genns given by Perkier, the presence of pedicels on the 

 odd ventral ambulacrum fits therii to that genus. The speci- 

 mens have tables of tlie triradiate typo and are vcm-v close to M. 



