200 COBRESPONDENCE. 



any degree of accuracy, and not only possible but not difficult. Mr. 

 Wenham's remark is the more amusing in that it comes from one 

 who professes to measure on paper the variation due to chromatic 

 dispersion ! 



Respectfully, &c., 



R. Keith. 



Notes on Prof. Eupert Jones's Memoir on the Variability 

 OF Foraminifera. 



To the Editor of the ' Monthly Microscopical Journal.' 



YoRKTOWN, Surrey, February 23, 1876. 

 Dear Sir, — Permit me to point out a few corrigenda in my paper 

 " On the Variability of Foraminifera," in the ' Monthly Microscopical 

 Journal' for February, No. Ixxxvi., p. 61, &c. 



1. My friend, Mr. H. B. Brady, whose works are quoted in the 

 memoir, reminds me that, with regard to Squamulina, described by 

 Schultze as calcareous and pore-less, and arranged in the Table, at 

 p. 89, as a " porcellanous " form, Mr. H. J. Carter has referred two 

 " arenaceous " species to this genus ; one monothalamous or sub- 

 multilocular, the other polythalamous. See his memoir " On Two 

 New Species of the Foraminiferous Genus Squamulina" &c.* 



2. Mr. Brady also assures me that the quadriserial arrangement of 

 the chambers" in Tetraiaxis (Table, p. 89) is not sufficient to distin- 

 guish it from Vahulina. He can only say that in the Carboniferous 

 strata there are more quadriserial than triserial Valvulince, and vice 

 versa in the Tertiary deposits and recent seas. 



3. He adds that Ellipsoidina (see the Table, p. 90) has its nearest 

 ally in CMlostomella, and both should closely follow Pohjmorphina, 

 though almost as much related to Biilimina ; and that Allomorphina 

 goes with the first two in Reuss's group of the " Cryptostegia." 



4. Archceosphcerina (in Table, p. 92) is now regarded by Dr. Daw- 

 son as being probably separated germ-like portions of the acervuline 

 variety of Eozoon. f 



5. Errata et Addenda. Page 62, line 34, /or 18 7-ead 20. 



P. 65, first footnote, add Dr. Wallich also has figured a similar 

 Planorhulina (?) with symmetrically perforated chamber-walls, in 

 'The North-Atlantic Sea-bed,' 1862, pi. 6, f. 20; and in his memoir 

 entitled ' Deep-sea Researches on the Biology of Globigerina,' 1876, 

 fig. 20. 



P. 73, last line, /or procure read produce. 



P. 87, third line from bottom, for 2-6 read 2-6. 



P. 88, line 8, for 7 read 6. 



P. 89, line 32, for Gryroporella read Gyroporella, 



Pp. 90 and 91, Ataxophragmium and Plecanium occur twice over 

 on account of the double character (both sandy and smooth) of the 

 types to which they belong. 



* 'Ann. Mag. Nat. Hist.,' ser. 4, vol. v., pp. 309-326, pi. 4 and 5. 

 t See ' Quart. Journ. Gcol, Soc.,' vol. x^xii., p. 73. 



