14 MCMURRICH. [Vot. III. 
Acontia were observed protruding at the cinclides, at the tips 
of the tentacles, at the limbus, and even through the base. 
They were always white. 
No sphincter muscle is present. ‘Yellow cells” are abun- 
dant in the endoderm of all the specimens examined. 
The tentacles are strongly entacmzous, the length of those 
of the inner cycle being 0.9 cm., and of those of the outer cycle 
0.15 cm. They are arranged in five cycles, their formula being 
6, 6, 12, 24, 48, although this arrangement was somewhat 
obscured by the members of the first two cycles appearing to 
form only one containing twelve tentacles. The mesogloea of 
the tentacles, as of the other portions of the body, is thin, and 
this is characteristic of all the species of this genus that I have 
studied. The muscles of the tentacles are simple and only 
slightly developed. On account of the absence of a circular 
muscle the tentacles are not infolded in contraction. 
The mesenteries are in four cycles arranged thus (Pl. III, 
Fig. 3): those of the first cycle (I.) only are complete, those 
of the second (II.) are large and well developed, those of the 
third (III.) quite small and apparently without mesenterial fila- 
ments, and those of the fourth (IV.) are minute processes of 
the mesoglcea of the column which do not project beyond the 
surface of the endoderm. The formula of the mesenteries is 
6, 6, 12, 24. The number of the stomata present was not made 
out with certainty, but there appeared to be two, situated as in 
A. annulata, an outer and an inner one. The longitudinal 
muscle bands are developed in the mesenteries of the first and 
second cycles; they occupy a considerable portion of the surface 
of the mesenteries, their elevation gradually diminishing towards 
the inner edge. The bases of all the mesenteries are dilated 
somewhat, but in those of the first and second cycle there is no 
pinnation of the dilated portion, while in the small and poorly 
developed mesenteries of the third cycle it was present. The 
parieto-basilar muscle is very weak. The reproductive organs 
were confined to the mesenteries of the second cycle. All the 
specimens examined were males with mature or nearly mature 
spermatozoa. 
Var. 8. Castanea.— This variety was found not very abun- 
dantly upon the under surface of blocks and fragments of coral 
rock along the shores. The color of the column is pale reddish 
