184 SPOLIA ZEYLANICA. 



tentacles. In the living specimen the bivium is generally 

 shghtly wi'inkled, and these grooves are much more accentuated 

 in spirit specimens. 



The ambulacral appendages are pedicels on the trivium and 

 papillae on the bivium. The. pedicels are arranged in three 

 broad rows with a few on the interambulacra. 



The papillse on the bivium are fairly large and are evenly 

 scattered. Theel's statement that there are true pedicels on 

 the bivium does not appear to be correct, since in the living 

 specimen none of the dorsal appendages have the suctorial 

 qualities of true pedicels. In no case have I found that the 

 dorsal appendages have the qualities of true pedicels, although 

 they may have a sucking disc strengthened by a perforated 

 plate. 



Internal Structure. — The calcareous ring is similar to that of 

 Act. miliaris, but is slightly variable. Usually there is a single 

 large stone canal attached to the right side of the dorsal 

 mesentery, and there is one large Polian vesicle. 



Spicules. — These consist of richly branched rods having a 

 length of 80 [jl and smaller dichotomously branched rosettes 

 similar to those of Act. miliaris, except that the branching is 

 richer. These are about 30 [k in length. There are also larger 

 irregular rods in the pedicels and papillse having a length of 



ISOj;.. 



Remarks. — This species is undoubtedly related to Act. 

 miliaris, but the deposits are always larger and more richly 

 branched. A specimen from Prof. Stanley Gardiner's 

 collection has given me some trouble owing to the nature of 

 the spicules. The specimen is full-sized and is light yellow 

 in colour, and has aU the characters associated with Act. 

 echinites, except the anal teeth, which are large and serrated 

 like those of Act. serratidens. The spicules are abundant, 

 but different from those of any known species. I have come 

 to the conclusion that it is a specimen of Act. echinites in which 

 the spicules have been partly dissolved, probably owing to the 

 action of formalin. 



General Distribution .■ — Indo -Pacific . 



