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Show 'Porcupine' Exp. 18/0: Atl. St. 3, 6, 13, 16, 17, 1 7a, 22, 24, 25, 27, 28, 28a; Med. 55. Distribution. Almost everywhere throughout the Atlantic and Pacific, but especially in the' southern parts of those oceans. All the species of this remarkable genus are "waifs and strays," and have no local or fixed place of abode. Like the Heteropods and Pteropods, they inhabit the surface of the sea; and being entirely at the mercy of the wind and waves, they are drifted hither and thither and are occasionally thrown ashore as far north as Caithness and Donegal on our own coasts, but not further northwards. I am not aware that any species of Ianthina has been recorded as fossil. Did the Equatorial or any similar marine current exist in the Pliocene or previous periods ? The apex of the present and other species is styliform, and apparently rudimentary or adapted to the embryonic stage of the animal. I may observe that although the food of the Ianthina is well known (see 'British Conchology,' vol. iv. p. 182), M . Henri Drouet, in his treatise on the 'Mollusques marins des lies Acores,' seems to have considered it herbivorous, when he mentions having often seen it floating in a reversed position, "en attendant sans doute la rencontre de quelque plante." Tasli graphically described its occurrence on the shores of Brittany, " oii quelquefois elles dessinent un ruban du plus beau bleu de plusieurs kilometres de longueur." With respect to the animal of Ianthina, d'Orbigny says, in his work on the Mollusca of the Canary Isles collected by Webb and Berthelot, " Cette bouche est munie lateralement de tentacules coniques portant les yeux a leur base externe." The Messrs. Adams state as to all the members of this family, " Tentacles short and obtuse, with pointed eye-pedicels at their bases, but without any trace of eyes ; " and they describe the Ianthinida as "blind." It is scarcely creditable that this simple question should not have been long ago determined and set at rest. 2. IANTHINA ROTUNDATA, Dillwyn. I rotundata (Leach, MS.), Dillw. Contrib. towards a History of Swansea (1840), p. 59 : B. C. iv. p. 186, frontispiece and pi. iii. f. 1 ; v. p. 214, pi. lxxvii. f. 1. 'Porcupine' Exp. 1869: St. 47. 1870: Atl. 16 (fragments). Distribution. British seas as well as the north-west of France, and Arcachon. Living specimens with the float attached were found by m e more than half a century ago in Oxwich Bay near Swansea, by Miss Hockin at Hayle in Cornwall, and by the late Dr. Battersby in the west of Ireland. Shells of 7. communis have also been found on our western coasts. Both of these species have several synonyms ; but as one of the objects of the present work is to serve as a further Supplement to ' British Conchology,' I will not repeat any of the synonyms which I have already given for our native Mollusca. |