DUBUN NATURAL HISTORY SOCIETT. 151 



count of this shell : ' Purple ocean shell. The creature which forms and inhabits 

 this shell is a native of the ocean, and lives frequently many hundred leagues 

 from any land ; but, having met with many of the kind between Bermuda and 

 the Western Islands in my voyage from Jamaica, it enabled me to communicate 

 the following account of thum. The creature probably passes the greater part 

 of life at the bottom of the sea, but rises sometimes to the surface, and to do so 

 is obliged piacium more, to distend an air-bladder, which however is formed 

 only for the present occasion, and made of tough, viscid slime, swelled into a ve- 

 sicular transparent moss, that sticks to the head of the animal at the opening of 

 the shell. This raises and sustains it while it pleases to continue on the 8ur> 

 face, but when it wants to return, it throws off its bladder and sinks." Though, 

 as I believe, this account of Brown's coincided with the generally received opi- 

 nion at that time, it will be found incorrect on referring to Forbes and Hanley, 

 -who, in their work on the British Mollusca, remark, that Cuvier observed there 

 was an anatomical connexion between the two bodies, i.e. between the animal 

 and the float, and this was oonflrmed by Dr. Coates, who, in the fourth volume of 

 the Journal of the Academy of Natural Sciences of Philadelphia, gives an inte- 

 resting account of his experiments on the float in the living animal. He found 

 that it was entirely secreted by the foot, and that, when a portion was removed, 

 the injury was rapidly repaired. After having quoted such high authority, it 

 may appear superfluous for me to remark, it is my opinion that, were the jan- 

 thina capable of inflating and exhausting this float, it would never be found on 

 our coasts in any profusion, as it would naturally, on the appearance of stormy 

 weather, retreat from the surface by exhausting the float, and remain at the bot- 

 tom until the gale had subsided. A very interesting paper on the janthina, from 

 the pen of that talented naturalist, Mr. William Clark, of Bath, is published in 

 the " Annals of Natural History," January, 1853, and as it contains much valu- 

 able information, I claim permission to make the following extract : — " This 

 genus has long caused embarrassment to naturalists, and is still a source of dif- 

 nculty in regard to the structure of the animal, and its natural position ; but I 

 think the obstacles to a true determination will disappear on attentive conside- 

 ration. The great stumbling block is the float, as it is called, or vesicular mass 

 attached to the foot, which has been considered an hydrostatic apparatus. This 

 idea is erroneous : the organ is the membraneous vehicle of the contents of the 

 ovarium and matrix, that has descended from under the mantle, and flxed itself 

 to the foot, for a very obvious purpose of the animal economy in reference to the 



Eulli, in the genial season. It is probable that as the animal, from its peculiar 

 abitat, cannot, like the tribes of the coasts, deposit the germs of reproduction 

 on marine substances, it makes use of the foot as a substitute, until its young 

 emerge from the agglomerated mass of capsules to shift for themselves ; and then 

 the temporary vesicular deposit is cast ofl^. I have seen a similar appendage to 

 the foot of the Pileopsis Hungaricus, and several other gasteropoda. That this 

 organ is not necessary for the flotation of the animal is strongly supported by 

 the fact, that the sexes are distinct, that many may be presumed the males, and 

 such often occur without the so-called float. Many of the Littorinte, with a shell 

 ten times more ponderous in proportion than theglobular delicate janthina, float 

 with the shell beneath and foot uppermost, in every direction, for days, without 

 descending from the surface of the waters." From this extract you will have 

 perceived that it is Mr. Clark's opinion that all the janthina are females which 

 are found with the float attached, and I must remark that I cannot agree with 

 him. It is well known this shell occurs only in shoals gregarious, if 1 may use 

 the term, on the surface of the ocean, and 1 should imagine that it was from one 

 of these shoals being drifted in at Kilkee I had the good fortune to meet with 

 them. Now, all the specimens I procured — and I obtained some hundreds— had 

 the float attached, and, therefore, all, adopting Mr. Clark's idea, would be con- 

 sidered females. Whether I obtained the entire or only a portion of the shoal, is 

 matter of doubt ; but I think I may safely conclude, I must, at least, have found 

 a fair average of the whole ; and I cannot conceive the strange anomaly of there 



