Miscellaneous. 



261 



4th. The Rudista, divided by distinctly marked zones in the mid- 

 dle of the cretaceous districts, form therein more or less extended 

 horizons, and always in the same respective position in relation to 

 the other fossils. 



Hence the distribution of beings in the terrestrial strata would not 

 be due to chance ; but, as M. d'Orbigny has already found with re- 

 gard to the Cephalopoda, it would be the result of the succession, in 

 an invariable order, of fauna more or less numerous, the perfect know- 

 ledge of which is hereafter destined to furnish the chronological 

 history of the ancient zoology of the globe. 



RISSOA HARVEYI. 



To the Editors of the Annals of Natural History. 



Dear Sirs, — The Supplementary Number of your interesting 

 periodical has reached me, in which you have been pleased to insert 

 a paper of mine, communicated to the Geological Society by .lames 

 Smith, Esq. of Jordan-hill. Allow me to correct a mistake in which 

 you had no share. It is stated (vol. viii. p. 515), that of the seventy 

 species of marine shells found by me in the post-tertiary deposit at 

 Largs, all were well-known inhabitants of the British seas, except 

 two species of Rissoa ; one of which had been previously found in 

 the Crag, and the other had been referred, with doubts, to the Ris- 

 soa Harvey i of Mr. Forbes. I should have said, the R. Harvey i of 

 Mr. Thompson of Belfast, by whom it had been figured and described 

 in a former vol. of the Annals (v. p. 96), and named in honour of 

 Mr. Harvey, the distinguished naturalist who discovered the shell. 



I am happy to add that my doubts have been completely removed. 

 I sent a specimen of the subfossil shell to Mr. Thompson, your very 

 intelligent correspondent; and by return of post he says, " the 

 subfossil is the veritable R. Harveyi, which I of course was much 

 gratified to see, two examples only of the recent shell having hitherto 

 been found." It is a remarkably beautiful little shell, and I am glad 

 that the subfossil specimens already outnumber the recent examples, 

 as two or three have been found by myself, and as many by the 

 Misses Mure of Warriston, whose sweet residence is adjoining to the 

 post-tertiary deposit. Though the other shells were known, there 

 were several of them of considerable rarity ; such as Cardium serra- 

 tum, of which only one valve was found ; Bulla truncata, Phasianella 

 tabulata, Rissoa cimex, Rissoa costata, Rissoa calathisca, Rissoa stria- 

 tula, Cemoria Flemingii, &c. 



Stevenston Manse, Ayrshire, Yours sincerely, 



18th April, 1842. D. Landsborough. 



NIGER EXPEDITION. MR. FRASER. 



The letter from Mr. Fraser, the naturalist to the Niger expedition, 

 dated from the mouth of the river Nun, W. Africa, August 14, 1 841, 

 read at the meeting of the Zoological Society, Dec. 14, which we 

 noticed in our number for January, contains some interesting facts 

 relating to the habits and habitats of certain animals. Among the 



