Inner lobe of large and convex; three ocelli ' left maxilla).
The sense-organs of medusae are of two kinds - first, organs sensitive to light, usually termed ocelli (fig.
The ocelli are seen in FIG.
The ocelli occur usually either on the inner or outer sides of the ten tacles; if on the inner side, the tentacle is turned upwards and t ®Q carried over the ex - umbrella so ®m r s ???.
In other cases ocelli may occur between tentacles, as in Tiaropsis (fig.
As has been described above, the endoderm may also contribute to the sense-organs, but such contributions are always of an accessory nature, for instance, concrement-cells in the otocysts, pigment in the ocelli, and never of sensory nature, sense-cells being Hydromedusae are of separate sexes, the only known exception being Amphogona apsteini, one of the Trachomedusae (Browne ).
In a state of maturity, and have ocelli; the female medusae remain attached and have no sense organs.
Gonosome with free medusae or gonophores; medusae usually with ocelli, never with otocysts.
Ocelli are seen at the base of the tentacles, and also (as an exception) groups of medusiform buds.
The sense organs are typically ocelli, never otocysts.
Gonosome with free medusae or gonophores; the medusae typically with otocysts, sometimes with cordyli or ocelli (figs.
- Trophosome only known in one genus (Thaumantias), similar to that of the Eucopidae; gonosome, free medusae with otocysts inconspicuous or absent, with usually four, sometimes eight, rarely more than eight, radial canals, simple and unbranched, along which the gonads are developed, with numerous tentacles bearing ocelli and with marginal sense-clubs.
Bearing gonads on the main canal, but not on the branches, with numerous hollow tentacles bearing ocelli, and without otocysts.
Ocelli, if present, are borne on the tentacle-bulbs.
Most insects possess a pair of compound eyes, and many have, in addition, three simple eyes or ocelli on the vertex.
The head is rather large, and is furnished at first with five simple eyes of nearly equal size; but as it increases in size the homologues of the facetted eyes of the imago become larger, whereas those equivalent to the ocelli remain small.
The head of a hymenopterous insect bears three simple eyes (ocelli) on the front and vertex in addition to the large compound FIG.
The broad head carries, in addition to the prominent compound eyes, three simple eyes (ocelli) on the crown, while the feeler consists of a stout basal segment, followed by five slender segments.
Have the head with two ocelli and three-segmented feelers; frequently as in the tropical " lantern-flies " (q.v.) the head is prolonged into a conspicuous bladder, or trunk-like process.
The young are prettily spotted with white and black ocelli, but the coloration of the adult is mostly very plain.
The sense-organs of medusae are of two classes: (1) pigment spots, sensitive to light, termed ocelli, which may become elaborated into eye-like structures with lens, retina and vitreous body; (2) organs of the sense of balance or orientation, commonly termed otocysts or statocysts.
X Ocelli and post-antennal organ of right side.
The sense-organs are covered over by flaps of the umbrellar margin (hence " Steganophthalmata "), and are always tentaculocysts, that is to say, reduced and modified tentacles, which bear usually both ocelli and otocysts, and are hollow.
The more proximal portion of the rhopalium usually bears one or more ocelli (oc).
Of the umbrella, EU, Ve, Fr, Tc, The ocelli vary greatly both as regards number and complexity of structure.
In Charybdaea there are no less than six ocelli on each of the four rhopalia (fig.
7); on the exumbral aspect there are two median ocelli (oc l, oc 2), a distal and a proximal, each of them a vesiculate ocellus with a lens, and on the sides of the rhopalium are two pairs of ocelli without lenses (oc. 1); sometimes also an additional seventh ocellus occurs, a pit-like structure without a lens, either between the two median ocelli, or placed asymmetrically near the median proximal ocellus.
The ocelli consist, as c, From the subumbrella of Aurelia aurita.
As a further advance, the pit becomes widened out into a cup, as in the lateral ocelli of Charybdaea.
The culminating stage of evolution is seen in the median ocelli of Charybdaea (fig.