214 Mr Barlow's illustration of' Facts connected with 



Although snakes are said to abound on the Gallapagos, yet 

 in all our excursions we never saw a single species. 



Shells and molluscous animals were not very plentiful. Crabs 

 of different species were very numerous, and some of them 

 very beautiful. The land-crab was common near the shore, and 

 appeared to be more gregarious than the other species ; they 

 were seen running about in small families of twenty or thirty 

 individuals, and when pursued covered themselves in the sand. 



On the 19th we left these islands and proceeded to the 

 north-west coast. 



All the islands of this group have a similar appearance. In 

 some places the coast rises into perpendicular rugged cliffs, 

 attaining the height of 200 feet, and in other situations it as- 

 sumes the form of a low sandy beach, separating some salt- 

 water lakes from the sea. The mountains are generally of a 

 conical shape, very gradual ascent, and moderate elevation. 

 The country, in most places, is pretty well furnished with 

 trees, except where the lava has run down, and in these situa- 

 tions very few vegetables grow. 



Art. II. — Illustration of' some Facts connected with the De- 

 vehpement of Magnetism by Rotation. By Peter Bar- 

 low, Esq.. F.R.S. Mem. Imp. Ac. Petrop. &c. In a Letter 

 to the Editor. 



Dear Sir, 



As I feel interested on some of the subjects alluded to in Mi 

 Christie's letter in your last number, I must beg to be allowed 

 to make a few observations, with a view to correcting any er- 

 rors which may have been committed in the reports of our 

 experiments. Neither Mr Christie nor myself can wish to 

 have any thing recorded but what we believe to be correct, 

 and therefore the plainer the facts connected with these ques- 

 tions are stated, the better. 



Mr Christie objects first, to that part of the historical no- 

 tice, in which it is said that " in repeating some of my expe- 

 riments,' 1 he was led to observe that property of iron which 



11 



