MEDUS.E. 137 



gonads on the proximal half of the canals, whilst in others the gonads reach nearly to 

 the margin of the umbrella. The gonads first arise in the proximal part of the canals 

 quite close to the stomach, and grow outwards towards the periphery of the umbrella. 

 Owing to the great extension of the walls of the radial canals in the region occupied 

 by the gonads, it is difficult in some specimens to mark the spot where the stomach 

 ends and the canals hegin. The gonads look as if the)' were situated upon lobes of 

 the stomach. The length of the gonads is independent of the development of the 

 generative cells, as a gonad extending over only half the radial canal has large ripe 

 ova. Sections show (fig. 10) that the ova at an early stage in their development are 

 among the endoderm cells, and that later on they move outwards to the ectoderm. 

 The section figured shows an ovum leaving the ovary and breaking through the 

 ectoderm. 



The tentacles are closely packed together round the margin of the umbrella, and 

 apparently form two alternating series, one projecting outwards and the other hanging 

 down. Although similar in structure, only those belonging to the former have a 

 conspicuous blackish basal bulb with a conspicuous black ocellus. The latter series 

 have a smaller basal bulb, either colourless or slightly pigmented, and either without 

 an ocellus or with a very small one. The basal bulb is on the inner side of the 

 tentacle ; it is a semi-circular thickening containing nematocysts and granules of 

 pigment, which cover the exterior of the bulb and also extend in radiating lines into 

 the interior. There is no spur-like projection at the base of the tentacles. The cirri 

 (fig. 9) are capable of extending to a great length. There is probably one between 

 every two tentacles, but very few were seen on the specimens. The free end terminates 

 in an oval knob containing large nematocysts (fig. 11). The ocellus is situated on the 

 margin of the basal bulb just below the velum. It is of an intense black colour, 

 spherical in shape, with a circular pit penetrating nearly to the centre (fig. 8). 



The cordylus is very small and club-shaped (fig. 9). The interior of club is 

 composed of endoderm cells which are connected with endoderm cells of the circular 

 canal (fig. 7). The structure of the cordylus resembles that of Laodice calcarata 

 (see Brooks, 1895). 



The specimens from Ceylon come nearest to Laodice calcarata which inhabits the 

 North Atlantic. They differ from it in having no spur at the base of the tentacles, 

 in having larger ocelli, and perhaps in colour and in size. 



Family : EUCOPID^E, Gegenbauk, 1856. 



Mitrocomium, Haeckel, 1879. 



Mitrocomium assimile, n. sp.- Plate I., fig. 3. 

 Description. Umbrella fairly thick, a little broader than high. Velum narrow. 

 Stomach short, with a quadrangular base. Four radial canals. Gonads upon the 

 outer half of the radial canals, forming large oval sacs. Four perradial tentacles. 



T 



