S_> FAMILY MILIOLIDA. 



relationship ^vith Fabularia, the pecuharity of whose structure consists in a higher develop- 

 ment of that tendency to subdivision of the general cavity of each chamber, of which M. 

 saworuiji presents a rudimentary manifestation. Through T'ahtlaria, again, the Milioline t}'pe 

 will be seen to be related to AlvcoRna, Orhiculvna, and Orhitolileii, all of which are characterised 

 by the like subdivision ; and it is most interesting to trace in some forms even of the highly 

 specialized OrbitoJites a return, as regards the conformation and aspect of the primordial 

 chamber and of that which immediately succeeds it, to the t}'pe presented by the corre- 

 sponding portion of an ordinary Miliola. 



114. Geographical Distribution. — Probably no Foraminifera are at present more 

 universally diffused than those of the Milioline type, which are most abundant between the 

 shore and a depth of 150 fathoms, but occasionally present themselves among the products 

 brought up from deep-sea soundings. The largest and best developed forms of this tj^pe, 

 such as that represented in fig. 33, are from the littoral zone of tropical seas. The shell is 

 itself perfectly free ; but the sarcode body of the animal by which the shell is usually invested 

 during life attaches itself to sea-weeds, zoophytes, &c., to which Miliola may often be found 

 adherent. 



115. Geological Distribution — The J/?72o/2Me type may be traced back in geological time 

 as far as the Lias, being rather abundant in the clay of that period from Stockton in 

 Warwickshire ; it is there, however, very small and delicate, presenting a condition exactly 

 analogous to that of recent forms brought up from depths of from 350 to 500 fathoms. It is 

 constantly present in the Gault, retaining its small dimensions, and also in the Chalk marl. 

 From the upper Chalk to the present period it is everywhere abundant in marine deposits, 

 having accumulated in certain parts of the Eocene period to such a vast extent that certain 

 beds of the " calcaire grossier" are almost entirely composed of aggregations of M. saxoruiii, 

 and are known as "Miliolite limestone." 



Genus VIII.— Fabularia (Plate VI, figs. 37,38). 



116. History. — The genus Fabularia was first distinguished by Defrance (xxix), who 

 applied that name to a body having a somewhat bean-like form, which occurs fossil in the 

 Paris Tertiaries, and which he had pre\aously confounded with Alveolina. He was, however, 

 totally ignorant of its real nature ; and it is now somewhat amusing to find him suggesting 

 that, as the irregular pores of its interior could not have contained polypes, it was probably 

 an internal shell enclosed like the " cuttle-fish bone" in the body of some Mollusk. Its place 

 as one of the Foraminifera was first indicated by D'Orbigny (lxix) ; but not being then 

 acquainted with its real structure, he grouped it among his Entomostegues. Subsequently, 

 however, he was led by more careful inquiry to perceive its essential conformity to the 

 Milioloid type, and to group it among his Agathistegues (lxxiii) ; and he correctly states that 

 it is most nearly related to Biloeulina, its difference consisting in this — that the cavity of each 



