Dublin Natural History Society. 3531 



considered the observation of the local Fauna of Ireland as most important, and by 

 which alone many of the doubts and errors of naturalists could be rectified. 



Mr. Kinahan referred to the statements of Yarrell and others on the spawning of 

 Gasterosteus, that they deposit their ova on the leaves of aquatic plants ; and stated 

 that he believed it was an error copied from previous writers, as he never found the ova 

 on plants, but invariably deposited in the dome of the nests, several of which were ex- 

 hibited to the meeting. 



Mr. Ffennell remarked on popular ideas relating to fishes, as respects their plenty 

 or scarcity, and alluded to the idea of pike being in the Lakes of Killarney, but from 

 his experience he believed there were none in the waters of Kerry, with the exception 

 of a small tributary to the Blackwater, at the bounds of the county Cork. 



Dr. Allman communicated an abstract of his views of the Medusae and Hydroid 

 Polypes. He believed that the essential part of the disk of a Medusa was the system 

 of gastro-vascular canals, which, at their origin, communicate with the stomach, and 

 thence radiate towards the margin of the disk. These canals are represented by the 

 tentacula of Hydra, which consist of two distinct layers, besides muscular fibres, and 

 thus, so far as structure is concerned, correspond with that of the gastro-vascular ca- 

 nals of the Medusae ; while the relation of the tentacula in the one, and the gastro-vas- 

 cular canals in the other, to the digestive system, is also precisely similar, in the two 

 groups. The peduncle of the Medusae is exactly represented, both in internal structure 

 and external form, by the anterior portion of the body of the Hydra. We have thus, 

 in order to convert a Hydra into a Medusa, only to suppose the external layer or der- 

 mis of the tentacula to be extended at each side into a kind of web, uniting the tenta- 

 cula to each other, and the posterior elongation of the body with its adhesive disk to 

 become suppressed, neither of which conditions involves any essential modification of 

 structure. The hydroid polypes generally are fixed animals, incapable of locomotion ; 

 in Hydra an imperfect locomotion is permitted, and the creature can detach itself from 

 the bodies to which it adheres, and slowly creep about by means of its tentacula and 

 adhesive disk, while in the Medusas the locomotive powers are carried to their maxi- 

 mum, and the tentacula, which in the polypes are free, are united by a membrane in 

 the Medusae, and thus constitute the large locomotive disk by which these beautiful 

 animals swim with rapidity and ease through the surrounding water. 



Mr. Ffennell then made some observations with reference to the par being the 

 young of the salmon, as he was anxious to remove doubts that existed in the minds of 

 some. He exhibited three specimens in a bottle, showing the bars on one well deve- 

 loped ; a second, in which the bars were fainter ; and a third, wherein the silvery scales 

 had nearly obliterated the bars : these were taken in a pool at Ballycroy, where they 

 had been left by the subsidence of the river, the intermediate water being too low to 

 admit of their regaining the main stream. He also exhibited another bottle, contain- 

 ing three specimens, taken at Killaloe; one an unusually large fry, in silvery state, 

 fully 10 inches in length, and large in proportion, on his way to the sea. Having con- 

 cluded, Mr. F. produced specimens of the pollan, taken in November, 1851, in Lough 

 Neagh, and some taken in Killarney on the 8th of May last; and observed on the dif- 

 ficulty of touching them without removing the scales. He directed the attention of 

 the meeting to the difference in the shape of the head and gill-cover of the specimens 

 from the two localities. 



This being the termination of the session, the meeting was adjourned to November 

 next ; in consequence of which the following gentlemen, proposed and secoudcd, will 



