MEDUSA. I. 



2 3 



seem to have contained mature sexual products, in so far as "the ova are prominent, and project out- 

 ward in grape-like clusters over the surface of the genital organs". This, indeed, does not seem to 

 suggest, that we have here to deal with young stages. It is not altogether excluded, however, that 

 such is nevertheless the case; we know other examples, where the eggs of a still young medusa may 

 develop into a considerable size and give the surface of the gonads a rugged appearance (see, for in- 

 stance, the following pages on Tiaropsis). The description, given by Ma as, is so clear and excellent, 

 that it cannot be misunderstood. It may be worth while, therefore, to call attention to the fact, that 

 Mayer (1910) identifies the two forms, an apprehension which he has not changed in his later work 

 (1915, p. 200), after having had the opportunity of examining new material of L. Jijiana from the 

 Torres Straits. 



During the German Deep-Sea Expedition a small Laodicea was found in the Gulf of Aden; it 

 was 5 mm in diameter and had about 96 tentacles. Vauhoffen (1911) referred this medusa to L. maasii 

 Browne. With regard to the size and the distribution of the large ocelli it agrees with L. indica 

 Browne, but cirri could not be pointed out with certainty. On the other hand, the presence of spurs 

 on the base of some of the tentacles evinces an agreement with L. maasn. It is an interesting fact, 

 that Vanhoffen did only find spurs on the younger tentacles, whereas such were apparently absent 

 in the case of the larger tentacles. Vanhoffen is of the opinion, "dass samtliche Tentakel einen 

 Sporn haben, dass er nur wegen der Krumrnung des Schirmrandes haufig nicht sichtbar ist und 

 besonders bei alteren Tentakeln undeutlich oder verdeckt wird . ." (1911, p. 22i). This agrees very- 

 well with what I have observed in Laodicea nndulata (see above). Vanhof fen's medusa reminds one of 

 the L. bigelowi Neppi & Stiasny (1911) from the Gulf of Triest, a small medusa (probably young), 

 7 mm in diameter with about 70 tentacles, some of which have basal spurs; cordyli, mounted upon 

 small bulbs, are found in somewhat smaller number than the tentacles; cirri are wanting. There can 

 be no doubt of the identity of this species with Laodicea undulata. 



The three forms of Laodicea from the Indo-Pacific region, mentioned above, viz. Jijiatia, 

 maasn, and indica, are undoubtedly nearly related. Their relation to the European Laodicea undulata 

 may, most adequately, be elucidated through a comparison between the latter and Maas's excellent 

 description of "L. fijiana var. indica" (= maasii Browne). The description and figure (Taf. V, Fig. 34) 

 of the flattened, open, square stomach, the four corners of which are drawn out into four "Zipfel", 

 agree exactly with the features found in L. undulata. The same holds good with regard to the gonads, 

 which, in the case of the North-Atlantic forms, have not been sufficiently thoroughly described up to 

 now. Maas mentions "Aussackungen, die nicht allein durch Faltung des die Geschlechtsprodukte 

 tragenden Ectoderms bedingt sind, soudern auch durch entsprechende Aussackungen des entodermalen 

 Raumes". Also in this respect we find a complete agreement with the facts, as I have observed them 

 in undulata. The length of the gonads is, in L. maasii, very variable, being, as a rule, 2 /s tne length 

 of the radial canal, but, in some cases, reaching nearly to the circular vessel. The number of tentacles 

 seems to be somewhat smaller in L. maasii than in equally-sized individuals of L. undulata; in this 

 regard maasii is more in accordance with calcarata and ulothrix. The shape of the tentacles is exactly 

 as in midulata. Ocelli are said to be found on about three-fourth of the tentacles of inaasii; in tinJulata 

 the number of ocelli is, as mentioned above, very variable. L. inaasii is said to possess a compara- 



