DEVELOPMENT OF AN APODOUS HOLOTHURIAN 505 
marked stage of development, but the succeeding tentacles are 
visible before the sixth and seventh are nearl}" as large as the orig- 
inal five. In the material of Chiridota at hand, I have found only 
three specimens in which the eighth tentacle can be seen. In each 
of these, the new tentacle is formed by the " secondary outgrowth ' ' 
beneath the right dorsal nerve pushing out dorsal to that nerve. 
Our eight-tentacled larva, therefore, has two tentacles in each of 
the dorsal interradii, while the two ventral interradii have only 
the primary tentacle in each, a noticeably symmetrical arrange- 
ment superficially, but one which leaves the left dorsal and mid- 
ventral secondary outgrowths of the hydrocoel entirely undevel- 
oped. Whether the ninth and tenth tentacles arise, as in Synap- 
tula, from the latero-ventral ''secondary outgrowths," I have 
been unable to determine, as no specimens were found with even 
the rudiments of these two tentacles. Becher ('07) has found an 
eight-tentacled stage in Rhabdomolgus, like that of Chiridota, 
while the adult retains permanently the ten-tentacled stage, like 
that of Synaptula. It is fair to presume, therefore, that Chiridota 
passes through such a stage. 
The calcareous particles in the eight-tentacled Chiridota larva 
deserve a word. The rods in the tentacles are fairly numerous 
and lie parallel to the long axis. The Trochoderma-like wheels 
are still to be found, scattered chiefly on the posterior part of the 
body. There are four or five heaps of Chiridota-like wheels in 
the interradii, two or three near each end of the body. While 
most of these wheels have six spokes, as they should have, some 
have seven, and a few have eight. It is noticeable that such varia- 
tions from the normal are much more frequent than in adult 
Chiridotas, where a wheel with more than six spokes is really very 
rare. 
SUMMARY 
1. The development of Chiridota rotifera is essentially like that 
already fully described for Synaptula hydriformis ( = Synapta 
vivipara, Clark, '98). 
2. The early larval stages of Chiridota (succeeding the 
gastrula) differ from those of Synaptula in the ovoid form, the 
