Contemporaneous Depositions of Salt and Gypsum. 277 



annoyed were brought down upon them with such force, that 

 a severe crushing was the sure consequence of their intrusion. 

 I regularly supplied them with fresh leaves, the parenchyma, 

 or soft spongy parts, of which constituted their food ; and, 

 during the period they existed in the larva state, they several 

 times changed their skins. By July 3. those first taken were 

 transformed to pupae ; and differed little in this state from the 

 larvae, except in being motionless, firmly attached to a leaf, 

 of a dusky black colour, with the thorax paler before, and 

 wider than the abdomen. On July 12. the perfect insects 

 appeared ; being only nine days in the condition of pupae. 

 On the 20th of the same month, both larvae and pupae were 

 taken from the plants, and in the locality, indicated above, 

 and went through their transformations in about the same 

 space of time. The only other species of Cassida taken in 

 this vicinity is the C. rubiginosa; a single specimen of which 

 occurred near the foot of the Sidlaw Hills, in May, 1836. For 

 excellent descriptions of both these, see Entomologia Edinen- 

 sis, p. 292, 293. The authors of this valuable volume would 

 confer a high boon on the lovers of entomology in Scotland 

 by the publication of a supplement, including descriptions of 

 those species given as addenda, and those indicated as Scottish, 

 throughout the body of the work. — TV. Gardiner. Jan. 20. 1837. 

 Contemporaneous Deposition of Salt and Gypsum. — The 

 contemporaneous deposition of salt and gypsum, as exhibited 

 on the Island of Ascension, was to me an interesting and 

 novel phenomenon. I walked to the windward side of the 

 island, the only part where it is exhibited, to witness the 

 circumstance. As you approach the shore, the rocks are 

 encrusted with salt and small beds of sulphate of lime ; but 

 on the table ledges of the rocks, which project a little to sea- 

 ward, and which are elevated about 20 ft. or 30 ft. above the 

 level of the sea, a heavy spray is continually thrown up. 

 Evaporation goes forward rapidly, by which the saline par- 

 ticles are left ; a constant percolation taking place at the same 

 time through the fissures or crevices of the rock. The sea 

 has undermined the base, and left a sort of cavern, the roof 

 of which is a thick bed of rock. Year after year the process 

 goes on. The spray, being thrown up into the hollow part of 

 the ledge, is evaporated, until a large quantity of the saline 

 contents are accumulated, consisting of muriate of soda, sul- 

 phate of magnesia, and sulphate of lime. The two former, 

 being soluble, are, of course, carried off by percolation through 

 the rocks: the sulphate of lime, being the more insoluble, 

 remains, and forms a bed of earthy gypsum 1 ft. or 2 ft. in 

 depth, with occasional masses of radiated crystals. The sea- 



