170 
long, the outer edge arched with a slight concavity in the middle, 
made more conspicuous through the coloration, the notch itself 
being dark coloured, and the corners being white. They are broadly 
in contact almost to the end of the arm. The characters of the 
ventral side in the adult specimens do not differ essentially from 
those found in the young specimens; I must merely emphasize 
that the oral shields are not pentagonal, but have the outer sides 
Fig. 33. Ophiozonoida picta H. L. Clark. Young specimen. 
distinctly concave, the outer part thus being distinctly narrower 
than the inner part; they may be said to be almost spearshaped. 
The madreporite alone retains the pentagonal shape. Also in younger 
specimens I find the oral shields more or less narrowed in their 
outer part, not so distinctly pentagonal as they are in the spec¬ 
imen figured by Clark (Op. cil. PI. 18, fig. 4). The ventral plates 
are generally more or less distinctly brownish and thus form a 
continuous brownish median band, lined on both sides with white, 
viz. the side plates. The outer edge of the ventral plates sometimes 
appears to have two distinet small whitish spots; it is, however, 
the inner, adradial point of the sideplates, which is thus coloured. 
The tentacle scales are single, as stated by Clark; but in the 
larger specimens there may be a very distinet elevated rim along 
