28 DR. GWYN JEFFREYS ON THE MOLLUSCA OF THE [Jan. 20, 



'Porcupine' Exp. 1870: Atl. St. 3, C, 13, 16, 17, 17a, 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 lanthinn 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 lanthina 

 is well known (see 'British Conch ologj',' vol. iv. p. 182), M. Henri 

 Drouet, in his treatise on the ' Mollusques marins des lies A9ores,' 

 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, " ou quelquefois elles 

 dessinent un ruban du plus beau bleu de plusieurs kilometres de 

 longueur." With respect to the animal of if/H^A/wa, 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 lanthinida; 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. 



1. rotundata (Leach, MS.), Dillw. Contrih. towards a History 

 of Swansea (1840), p. 59 : B. C. iv. p. 18G, frontispiece and pi. iii. 

 f. 1 ; V. p. 214, pi. Ixxvii. 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 me 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 I. 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. 



