347 



Fig, 14. MILIOLA 

 (QUINQUELOCU- 



I.INA). 



One of HIP " Porcel- 

 lanous" Foramini- 

 fera: living. (After 

 Schultze.) 



of alliance (besides their pseudopodial and physiological characters), as well as exceptions in their 

 structural characters; for (1) some individuals of the porcellanous one-mouthed kind have connecting 

 passages between their inner chambers ; (2) some of the perforate forms begin with the usual hyaline 

 shell-structure, but become coarse, imperforate, and sandy with advancing age. (3) Moreover, some of 

 the smooth porcelkma become sandy as they grow. (4) Some, also, of the same kind secrete little or no 

 shell-matter, and have sometimes merely a covering of membranous consistence, like that of some of 

 the shelled Anirebans, many of which latter group we may remark, though they are not calcareous, 

 have the habit of taking up sand to stiffen their tests. (5) Some of the arenaceous 

 kinds send out pseudopods from between the sand-grains embedded, but not 

 cemented, on their surface, and do not appear to have the usual large aperture 

 for the stolon ; and there is said to be even a simpler kind, merely a little morsel 

 of sarcode containing sand, not as a coating, but mixed up vaguely with it,* 

 more abundantly, it seems, than the grains of sand found in some of the more 

 gluttonous and coarse-feeding of the Amcebcc, and serving perhaps to give a kind of 

 general stability to the little Moneral organism. The largest known of the Arenacea 

 are Parkeria (after W. K. Parker], and Loftusia (after W. K. Loftus). 



Those Foraminifera which have a white, opaque or compact, non-porous, 

 porcellanous shell, without perforations for the passage of pseudopods from every 

 part of the enclosed body, comprise six well-known, typical forms. Around 

 these an almost endless series of more or less allied forms, having the same 

 essential characters, but varying in modes of growth, and often almost imitating one 

 another, especially in their young stages, may be grouped by zoologists. There is, 

 first, the Cornuspira (horn-coil, Fig. 16 4 ), a simple thread of sarcode coiling flatwise, and coated with 

 the usual opaque shell open at the end. Becoming constricted at intervals, and losing its circularity, 

 it seems, if we put all the varying individuals in a series, to pass into a Miliola (millet-seed), which 

 is folded up and down, and is pinched in at the turns whether these come exactly opposite 

 to each other on the two sides of the shell, as in BllocuUna (two-chambers) and Spiroloculina 

 (spiral chambers, Fig. 16,); or do not equally match on opposite sides, but leave three or five 

 folds visible on the unequal faces, as in Triloculina and Quinqueloculina (three and five chambers, 

 Figs. 14, 16 3 ). Some individuals when young, and even in the adult state, make but an 

 imperfect second chamber in the turn of the shell ; and, beginning like the retort-shaped Diftiugice, 

 seem to fail in advanced growth, as the Adeloeina (not manifest, or uncertain). The Miliolida} 

 may be said to be cosmopolites, in all seas ; and they are frequent in a fossil state, especially at Paris. 

 Again, some begin with the circular, or with the alternate or agathistegian (ball-of-thread-like) folds, 

 but go off with a straight growth, chamber after chamber sometimes narrow, 

 as Articuliiw (joint-like), or broader as in Vertebraliiia (vertebra-like), common 

 in the Red Sea. In all these the terminal aperture, whatever its relative 

 size may be, gives out the sarcode to make pseudopods, but not to go back 

 over the whole shell as a coating film. 



Another kind of shell among the porcellanous group has often a delicate 

 pearly whiteness ; and begins with one globule of sarcode, which gives off by 

 one stolon a half-moon-shaped segment, which, in its turn, gives off two or 

 more stolons, and a largei-, curved, narrow segment j and this produces a 

 transversely-longer crescentic addition with additional parallel and advancing 

 stolons, until chamber after chamber lengthens and widens the shell in its 

 growth, often curving elegantly (on a plane). It is pierced at its terminal 

 edge either with separate holes or a branching rift (as if the holes had 



run one into another) ; and thus we have the Peiieroplis (a fancy name), with perforate edge, 

 or Dendritiiia (Fig. 30), with "tree-like" mouth. Often Peneroplis grows quite narrow and straight 

 after a feeble youth of spiral growth, and then it is like a crozier. It is common in the Red Sea and 

 Mediterranean. 



Orbiculina (circle-like) is formed on somewhat the same plan, but it is not so pearly, and from 

 * Carpenter, " Foraminifera, " Encycl. Brit, ix., p. 375. 



Fig. 15. 



(After Schultzc.) 



One of tlie "Vitreous" Forami 

 nUera : livimr. 



