I. OLINDIOIDES FORMOSA gen. "nov., sp. nov. 



For some years past one species of veiled medusa, in particular, has been attract- 

 ing the notice of the members of the Misaki Biological Station, by its large size, the 

 beautiful variety of its colors, and some peculiarities in the form and arrangement 

 of its tentacles. Attending, among other things, to the study of the veiled medusae, 

 my attention was naturally drawn to the above-mentioned species, and with the 

 generous assistance of the Director of the Station, I have been enabled to collect 

 enough material for study, the principal results of which are given in the following 

 lines. It is a great pleasure to me to extend my best thanks to Professor Mitsukuri, 

 the Director of the Station. 



The medusa in question has proved on study to possess many striking points of 

 resemblance to the Mediterranean species Olindias mulleri Haeckel; but for reasons 

 which will appear farther on I have decided to form a new genus for it, and propose 

 the name of Olindioides formosa for the species. Further, I have come to the con- 

 clusion that the genera Gonionema and Halicalyx are closely, and the fresh-water 

 genera Limnocodium and Limnocnida more distantly, related to the new genus, and 

 these relationships will be discussed. 



There are some facts connected with the occurrence of the medusa that deserve 

 notice. So far as my experience goes it is found only from December to June or 

 July. The examples collected in December are all immature, with the diameter of 

 the disk not over 20 millimetres or so, and although a few stragglers may be met 

 with in July and August, they generally appear to be in a dilapidated condition. It 

 must, however, be remembered that these limits are subject to variation from year to 

 year. Another fact worth noting is that Olindioides formosa is a bottom species, 

 and none but weakened or injured examples have been caught at the surface. The 

 best season for collecting the medusa is March and April, when a large number of 

 fishermen do trawling at various depths off the Station, and by sailing from one boat 

 to another as the trawls are hauled in, one can, on. successful occasions, easily get a 

 few dozen specimens. The medusa appears to confine itself to the depth of from 

 20 to 30 fathoms, although my experience has not been varied enough to enable me 

 to make any very positive statement on this point. 



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