412 
Mr Menon , Notes on Semper s Larvae. 
As in Zoanthella there is a uniform covering of small cilia ; 
but what characterises this form is a ring of especially long cilia 
attached to the bottom of a groove running round the body at about 
a third of its length from the oral end. This circular band is not 
so markedly iridescent as the longitudinal band of Zoanthella. The 
cilia are directly orally and work together rhythmically as if they 
formed a rhythmically vibrating membrane (the movement can be 
best compared to that of the umbrella of a jelly-fish). The ciliated 
band pulsates very rapidly for a few seconds, then stops for a short 
interval, and then pulsates again. The result of this movement 
of the cilia is that the larva darts through the water, aboral end 
directed forwards, for a few millimeters, then rests on the bottom 
of the vessel, and then darts through the water again — its orbit 
thus consisting of a number of small arcs. These movements 
were best observed in the youngest specimen, which was remark- 
ably active. The older specimens, when not lying on the bottom 
of the vessel, suspend themselves in the water, the circular band 
of cilia moving very slowly and only occasionally. The movement 
of this ciliated band thus differs from that of the ciliated bands of 
an ordinary trochosphere. 
The mouth is a quadrangular opening. I have not found the 
oral papillae mentioned by McMurrich. The wall of the stomo- 
daeum is thrown into longitudinal folds and grooves which cor- 
respond to the mesenteric chambers and mesenteries. They be- 
come less marked towards the mouth. There are five ridges 
projecting into the lumen of the stomodaeum and corresponding 
to the dorsal and the two pairs of lateral primary mesenteric 
chambers ; there are four grooves opposite the attachments of the 
dorsal and lateral pairs of mesenteries to the stomodaeum. The 
ventral region is occupied by one large groove, the siphonoglyph. 
These structures can be made out in the living larva as well as in 
sections, and are thus quite natural. 
The inner organisation agrees in all essential respects with 
that of Zoanthella. A siphonoglyph can be distinctly made out 
in larger specimens. It lies, as is usually the case in the Zoan- 
theae, on the side of the stomodaeum, which is on that account 
designated ventral. In earlier stages the siphonoglyph appears to 
be wanting, its lower end is not produced into a lappet. 
There are twelve mesenteries, six large and six small, having 
the same arrangement as in Zoanthella. The ectoderm has, in 
addition to ordinary cells, gland cells, some of which have coarse 
granules and others clear, non-staining, reticulate contents. Pig- 
ment cells with brown or yellow granules are present, but are not 
so numerous as in Zoanthella. There are two kinds of nematocysts 
(fig. 9), the larger of which are much more elongated relatively 
than the larger nematocysts of Zoanthella. These occur in large 
