696 Froceedings of the Royal Irish Academy. 



all probability, will eventually be found there, except, perhaps, 

 Margelis pyramidata. 



My visits to Port Eiin have been principally duiing April and 

 May, and not during the summer months : conseq^uently my knowledge 

 is somewhat limited to the spring forms. 



The Leptomedus^ of A^alencia do not show so close an agreement 

 with those of Plymouth as the Anthomedusae, but the difference is not 

 great. There are only three species which I have not taken at 

 Pljrmouth : — Dipleurosoma typicum, JTelicertidium. octocostatum^ and 

 Laodice calcarata. 



Dipleurosotna typicum is a remarkable Medusa ; and until more is 

 known about its distribution, and especially its life-history, my 

 remarks must be of a speculative nature. There ought now to be no 

 difficulty in tracing its life-history, as the ova remain attached to the 

 Medusa until the planula stage is reached,^ and the planulse could be 

 reared in a " Plunger" aquarium, such as is used in the Plymouth 

 laboratory. This Medusa was very scarce during my visit in 1896; 

 but the Misses Delap reported shoals in 1897 and 1898. It has not 

 often been recorded, but its distribution is wide : — JS'ewfoundland, 

 [Norway, south coast of Ireland, Kingstown Harbour, and Brighton. 

 Its occurrence at Brighton (1879) tends to show that the Medusa 

 passed up Channel on that occasion. 



The second species, not taken at Plymouth, llelicertidium octo- 

 costatum), is a member of our noi-therTi fauna. It is common in 

 Scotland, but rarely taken in the southern pai-t of the British area. It 

 was only taken once at Valencia in 1897, and has only been once 

 recorded for the English Channel — at Falmouth, by Cocks, when it 

 was abundant in the summer (1849). This species has such well- 

 marked characters (eight radial canals and eight large gonads) that 

 there should not be the slightest difficulty in detennining the sole 

 member of the genus. It is not likely, then, that this species would 

 have escaped observation at Plymouth if taken in the tow-net. 



The thii'd species, Laodice calcarata, has a wide distribution ; but 

 its esact range cannot be decided until the "good species" of the 



1 Dijjleurosonm typicum. — Last summer the Misses Delap successfully reared 

 several dozen planulae up to a liydi'oid form. The hydroids are still alive in an 

 aquarium, hut have remained stationary in growth throughout the winter. From 

 the desc/iption and drawings kindly sent to me by the Misses Delap I am inclined 

 to think that the hydroids have not developed very far. It will be best to wait 

 for further development before publishing a description of thehydroid, which, at its 

 present stage, appears to belong to the genus Cuspidella (March, 1900). 



