KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 19. N:0 4. 5 



bigenerine Textularice associated with very large nodosarine Lituolinw, Valvulinoe and 

 Uvigerina; present themselves in great abundance. The Nummulinidaj are represented 

 by strongly developed AinpMsteginw. 



Polymorphina, Rotalina, Orbitolites, Opercidina are strikingly absent; Polystomella is 

 scanty and stunted. 



The want of silicious sand in the ooze raay account for the fact, that aggluti- 

 nating forms, which in other places generally construct their shells of such matter, 

 on this sea-bed nsually build them up of ealcareous fragments. Soinc species seem to 

 choose for their building-materials the finest mud, which imparts to the shell a fine 

 grain and a certain degree of smoothness. As a substituts for silicious sand others 

 again make use of available sponge-needles intermixing them with ealcareous debris. 

 Only a few forms succeed in conglutinating their shells entirely of silicious sand-grains. 



It is however somewhat surprising to meet with Lituolina- and Valvulina-forms 

 constructed of such sand, and associated with them their nearest kindred or even the 

 same species incased in ealcareous sand and greatly differing in outward shape. 



This association on a bottom so deåcient in silicious sand, and the apparently 

 decided predilection for that material found among these silicious forms, as well as their 

 difference in shape from their ealcareous congeners, leave the systematist in some sus- 

 pense as to the true relation that one set bears to the other. For the present I am 

 inclined to consider their differences to be but of varietal importance. 



Some twenty years ago Professor v. Reuss assigned to the agglutinating reticu- 

 larian Rhizopods a separate place in his system by establishing the suborder arenaceo- 

 silicious. To this group were referred by its author both those genera the forms of 

 which are not invariably arenaceous, as Valvulina, Bulimina, Textularia, and those 

 genera which are considered as constantly agglutinating, as Lituolina, Trochammina 

 etc. Of these agglutinating genera Lituolina, Trochammina and Valvulina only were 

 at the same period, or rather somewhat before, plaeed by Carpenter in the »arena- 

 ceous» sub-order, (Introduct. p. 140.) Thus the two authors differ widely as to the 

 compass of this group. Besides, the German naturalist seems not to have recognised 

 other agglutinating forms than »silicious», whilst the English authors state that at least 

 some forms of this sub-order constiaict their tests of foreign materials of any descrip- 

 tion — both silicious and ealcareous, (Carp., Introd. p. 143; Brady, Carbonif. and 

 Perm. Foramf., Palasont. Soc. 30, p. 9.) 



The impropriety of splitting up such genera as Textularia, Bulimina etc. in order 

 to get their agglutinating forms ranged within the silicious group, is manifest; and as 

 an illustration of the impropriety of the character itself — »silicious» — may serve 

 not only the Lituolina3 and Valvulinas just mentioned, from my own dredgings, but also 

 the bigenerine multiserial forms of Textularia, which all were referred to this sub- 

 order by its author, but which often have been found »ealcareous». Terquem also 

 States, that he met with Verneuilina from the Oolitic strata both of ealcareous and 

 of silicious construction. (Les Foramf. du Syst. oolit.; Bullet. Soc. hist. nat. Depar- 

 tement de la Moselie, 1868, 11, p. 39.) 



