66 REPORT — 1844. 



that this mollusk underwent a metamorphosis quite similar to what has been observed 

 in the Dorides and Aplysiag, the larva being furnished with locomotive ciliated discs, 

 and enclosed in a delicate nautiloid shell, where an operculum protects it from all ex- 

 ternal intrusion. 



On a New Genus of lleUanthoid Zoophytes. By Professor Allman. 



Professor Allman brought before the Section a Helianthoid zoophyte which he had 

 just discovered at Cruick Haven, upon the southern coast of the county of Cork, and 

 which, as far as he had as yet been able to determine, must probably constitute a new 

 genus; he refrained, however, from naming it, in consequence of the limited number 

 of works which he had had an opportunity' of consulting since its discovery. The 

 zoophyte is one of extreme beauty, and constitutes a connecting link between Actinia 

 and Lucernaria, being distinguished from the former by its capitate tentacula, and 

 from the latter by their arrangement in two uninterrupted series. Its anatomy closely 

 corresponds with Actinia, but in the capitula with which the tentacula terminate, are 

 to be found certain most singular organs. These consist of transparent oval capsules, 

 having coiled up within them a very long fibre, which, under a high power of the 

 microscope, is itself seen to be furnished with a spiral groove, with closely approxi- 

 mated coils, and traceable along its entire length. When the capsules are liberated 

 from the tentacula, a most curious phsenomenon is presented. The spiral fibre which 

 they contain is forcibly ejected through one end of the capsule, and, uncoiling itself 

 as it escapes, is rapidly shot across the stage of the microscope. Professor Allman 

 insisted on the analogy between these bodies and the darts described by Corda in the 

 tentacula of Hydra fusca, and was of opinion that they are organs gifted with the 

 property' of inflicting envenomed wounds upon the animals which constitute the 

 food of the zoophyte. They are accompanied by other bodies whose structure ap- 

 pears to be that of a fibre rolled into a close spiral, but not furnished with a capsule. 



On the Structure of the Lucernarice, By Professor Allman. 



In this communication certain undescribed peculiarities in the anatomy of these zoo- 

 phytes were laid before the Section, and the existence in the tentacula and other super- 

 ficial parts of the animal, of organs analogous to the darts of Hydra, and to the spiral 

 bodies of the Helianthoid zoophyte already described, was demonstrated. The posi- 

 tion of the Lucernarise in the animal kingdom is in close relation with the Acalephse 

 — a group with which they would appear to be more nearly allied than with the 

 proper zoophytes, though they constitute a remarkable and beautiful transition be- 

 tween the Pulmonigrade Acalephse on the one hand, and the Helianthoid zoophytes 

 on the other. 



Mr. Thompson read a paper entitled ' Additions to the Fauna of Ireland,' com- 

 prising a number of new species of Invertebrata, specimens of which were exhibited 

 to the meeting. He called attention to the desirableness of the additions to the fauna 

 and flora of Ireland and of Great Britain being brought forward regularly at the 

 meetings of the Association, together with an exhibition of specimens of the respective 

 species whenever practicable. 



Mr. Thompson read ' Descriptions of Pterochilus, a new genus of Nudibranchiate 

 MoUusca, and two new species of Boris,' by Joshua Alder and Albany Hancock. 

 This communication was illustrated with splendid coloured drawings of the species 

 executed by the authors, who likewise sent for exhibition drawings of the following 

 four species described by them since the last meeting of the British Association, viz, 

 Proctonotus mucroniferus, Eolis alba, E. Farrani, and E. violacea. 



Dr. Carpenter communicated to the Section some observations on the position; 

 which he deemed ought to be given to the compound Ascidians in the zoological scale. 

 In opposition to Milne Edwards, he considered that the compound Ascidians should 

 be placed with the MoUusca, and the Ascidian Polyps with the Radiata, 



