8 ORGANS OF SENSE. 



1-200'" in size. The males cannot be distinguished from the females either by shape or size 

 of the body, or by the form of the sexual glands." Will fancied these glands had a greenish 

 glitter in the male, which was not present in the female. "The testicles are likewise twisted 

 sacs filled with spermatozoa. The latter consist of a thick oblong body, measuring 1-800"' 

 and an extremely slender, long tail, which is only visible during vibration." Will found at all 

 times as many males as females. 



Organs of Sense. — The lips and their appendages, the marginal tentacula, and the bulbs 

 at their bases, may be enumerated under this head. The lips and the tentacula are instruments 

 of touch and prehension, the former chiefly for the purpose of seizing the animal's prey, and 

 sometimes, as I have seen in the case of a Geryonia, for anchoring the body. The lips vary 

 much in form. They are sometimes (as in Circe, most species of Thaumantias, and 

 Polyxenid) simple lobes ; in other cases (as in Turris, Geryonia, and Oceania) fimbriated lobes ; 

 in Bougainvillea and Liznia, they are furnished with single or branched tentacular processes, 

 reminding us of the curious gland-tipped cirrhi, which are so conspicuous in the genus 

 Cassiopeia among the higher Discophorce, and which were long supposed, and are usually 

 still described to be roots or suckers for the purpose of absorbing nourishment. In Sarsia, 

 Slahheria, and Steenstrupia, the lip is a simple ring around the orifice of the tubular digestive 

 cavity. The tentacula in all our British examples of the naked-eyed Medusse, are simple and 

 usually filiform, though highly contractile, and in some species often reduced almost to a 

 point. In Slabberia we have an abnormal form of these organs, their termination presenting 

 the appearance of a bulb. In Euphysa, the single tentacle is clavate and different in structure 

 from that of any other British genus. In the same curious form all the tentacles except one are 

 aborted, a remarkable modification seen also in Steenstrupia. In a new species of Geryonia, 

 here figured, alternate tentacles are glanduliferous. In not a few species there are two 

 varieties of tentacles placed in a single series round the margin, but the majority have the 

 tentacles only of one kind. 



At the base of the marginal tentacula or cirrhi there are present in a great many of these 

 animals coloured spots or bulbs. In some species (as in Thaumantias pilosella, Slahheria 

 halterata, Willsia stellata, Lizzia octo-punctata, &c.) these points are very strongly coloured, 

 and from their magnitude indicate the course of the animal when in motion, appearing like 

 a circle of gems in the water. Where some of the tentacula are aborted (as in Steenstrupia 

 and Euphysa), they are not aborted with these organs, but are all conspicuously developed ; 

 in many forms only certain tentacles have bulbs at their bases. In other forms, the tentacula 

 are present and highly developed, but no coloured spots or bulbs are seen at their bases, as in 

 certain kinds of Geryonia and Circe. When these bulbs are examined under the microscope, 

 we find their organization more complicated than at first glance it would seem to be. In the 

 majority of species, perhaps in all, these bulbs, whether conspicuous from colouring or not, 

 contain a small cavity quite distinct from any coloured spot which may be present. The 

 former is the otolitlc vesicle, the latter the ocellus. 



The otolitic vesicle, which, from analogy and its peculiar structure, is considered an 

 organ of hearing, is a small spherical sac developed in the midst of the granular substance of 

 the bulb, and containing more or fewer minute vibrating bodies. Will has described the 

 otolitic vesicle and its contents in a Geryonia as follows : " The auditory vesicles are seated 



