LIMOPSIS. 163 



tantalizing not to see the enclosed treasure as a reward 

 for my patience. I was more fortunate, however, in 

 the specimens which I obtained the following year. 

 One of them came out during the night and displayed 

 itself. The foot was the only part visible outside. The 

 mantle appeared to have no tube, although I saw dis- 

 tinctly through its open folds the gills regularly flapping. 

 The alimentary and branchial orifice was in front. The 

 excretal orifice was at the broader end, where fsecal 

 pellets were occasionally ejected. The Limopsis ex- 

 tended the foot beyond the narrower end of the shell, 

 and after attaching the extremity to the side of the 

 glass vessel, and contracting the foot above, it drew 

 itself up to the further point, like warping a vessel to 

 the anchor when moored; it then again stretched out 

 the foot, using on each occasion the whole of the elon- 

 gated disk or sole, in the same manner as a Planaria, 

 Repeating this operation, it contrived by slow degrees 

 to crawl up the side, and travelled four inches in two 

 hours, being at the rate of a mile in little less than three 

 years and eight months. On reaching the top it spun 

 with its foot a very fine and almost transparent but tena- 

 cious thread, the end of which it fixed to the inside rim 

 of the vessel; and it remained for twelve hours thus 

 suspended, with the beaks of its shell downwards. When 

 I emptied the bottle, and put in fresh water, the byssal 

 thread still continued fixed, and the Limopsis kept its 

 former place. It only loosed its hold after having a slight 

 degree of force used. In this respect the strength and 

 duration of the attachment differed from that by which 

 Sphcerium lacustre orKellia suborbicularis suspends itself. 

 The process, however, is the same in all cases, whether 

 it be the occasional secretion by the last-mentioned bi- 

 valves of a slight gossamer filament or the production 



