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ON A NEW GENUS OF NUDIBRANCHIATA. 



Fam. Elysiad^. 



By the Eev. J, E. Tenison Woods, F.G.S., F.L.S., Coee. 

 Mem. Eoy. Soc. Tas., &c. 



The Elysiadse are shelless mollusca with no distinct mantle 

 or respiratory organ, all being performed by the ciliated 

 surface of the body. The stomach is central ; the hepatic 

 organ branched, extending almost the whole length of the 

 animal ; eyes sessile, and tentacles simple or obsolete. 



There are five known genera of the family, viz.: — Elysia, 

 with tentacles ; Act^opnia, leech-like and with tentacles ; 

 Genia leech-like, linear dorsal tentacles ; Limapontia, head 

 truncated and with arched lateral ridges ; Ehodope, worm- 

 like. 



To this family I have found an addition of marked and 

 peculiar generic character. This new genus I propose to dedi- 

 cate to Mr. Morton Allport, as a slight mark of appreciation 

 of his great services to science and acclimatization in 

 Tasmania. 



ALLPOETIA, Nov. Gen. 



Corpus expansiim, tenue, antice et postice omnino complanatum, 

 occulis suhmarginatis. 



Allportia expansa. n. s. Corpus supra olivaceiim, pede pallidiore ; 

 occulis appoximatis punctis parvis atratis numerosis, compositis ; infra 

 lijieis ramulosis albis (hepaticis ?) conspicuis. 



Animal expanded thin, leaf-life, with no distinct foot, eyes 

 anterior ; body without tentacles or ridges. 



Allpoetia expansa. n.s. Animal of a deep olive above, 

 smooth ; eyes close together and slightly raised about one 

 fourth of the whole length within the anterior edge. Under the 

 lens the eyes appear to be composed of many minute dots. No 

 other organ visible above. Foot much paler, the hepatic organs 

 appearing as a creamy white branching plume down the median 

 line. Length, 30 ; breadth, 20 millimetres. Common under 

 stones among the rocks at Southport. 



This singular mollusc moves with some rapidity like a pale 

 gelatinous expansion of extreme tenuity. Though without 

 shell or apparent muscles, it has such contractile power that 

 it can move itself in any direction and raise itself nearly 

 erect. While the highly organised testaceous mollusca can 

 move only with difficulty, this delicate creature can recover its 

 position at once easily, even when placed on its back. It is of 

 such extreme tenuity, however, that on being placed in spirits 

 it becomes opaque, and the details of its structure are lost. 

 Type specimens are preserved for the Museum. 



