Dr Davy's Observations on the Centipede. 385 



formation, and in abundant quantity, of lithate of ammo- 

 nia. This activity of functions, I believe, was connected with 

 the growth of the centipede ; for at the end of the month it 

 appeared decidedly increased in size. Had it not escaped, 

 this would have been determined with precision by weigh- 

 ing. 



The snail, which, in the heading of this notice I have called 

 the large snail of the West Indies, is, I believe, identical 

 with Helix ohlonga of Linnseus. It is very common in the 

 island of Tobago, less so in St Vincent, and is not met with 

 in Barbadoes. The specimens I have seen have been about 

 four inches in length, and about two in width. It burrows, 

 hiding itself under ground during the dry season. There, 

 too, it deposits its eggs. It appears abroad in damp nights, 

 and by day in rainy or showery weather. It is believed to 

 feed entirely on vegetables. 



Its eggs, those I have seen, have been about two inches 

 long and about six-tenths of an inch in their short diameter. 

 They have a brittle, semi-transparent shell, which, I find, is 

 composed of carbonate of lime, with a little animal matter, 

 and a just perceptible trace of phosphate of lime. Their 

 contents, in their early stage, judging from one that I have 

 examined, are a viscid fluid of uniform colour, white, with a 

 just perceptible tinge of yellow. There was no appearance 

 of yolk. The white was found to be of specific gravity 1060, 

 carefull} weighed. It was coagulated by heat, and was ren- 

 dered opaque by corrosive sublimate and nitric acid, much 

 in the same manner as the albumen ovi of the common fowl ; 

 but the coagulum was less firm, — yet, as firmed by heat, suf- 

 ficiently so, to bear the inversion of ^the vessel without its 

 flowing. 



The excrement which this snail voids is large in quantity, 

 in consolidated cylindrical masses, — casts seemingly of the 

 tube from whence they are discharged. What I have ex- 

 amined I have found to consist chiefly of two kinds of mat- 

 ter, viz., one, the chief portion, of a dark olive-green, formed 

 principally of the debris of the vegetable food, as was indi- 

 cated by its appearance under the microscope ; the other, 

 almost white, soft when voided, of uniform appearance and 



