363 HENRY B. BRADY. 



dividuals are often of smaller size. On the other hand, such 

 genera as Veriehralinq, Articulma, Nuhecularia, and Dacty- 

 lopora are unknown in deep water ; whilst the helicoid and 

 annular types, Peneroplis, OrhicuUna, Orhitolites (except the 

 anomalous 0. teyiuissiimis) , and Alveolina, are not to be found 

 beyond the Coral Zone of Forbes. 



The MiLioLiDA differ from the other families of Foramini- 

 fera in the structure of their shelly investment, M'hich is 

 normally porcellanous and imperforate. By "porcellanous" 

 is meant that it is of compact homogeneous texture, white 

 and polished by reflected light, and, in thin sections, by 

 transmitted light, of an even brownish tint. Young shells 

 are opalescent and diaphanous rather than vitreous and 

 transparent. In the adult condition all are imperforate, and 

 being so the thicker portions are never tubulated, nor is there 

 any supplementary skeleton. The tests of even the roughest of 

 the sandy Miliola have a distinct imperforate shelly basis, 

 easily recognised in transparent sections if sufficient care be 

 taken not to disintegrate them in grinding. In respect to 

 the genera Peneroplis and OrhicuUna, it may perhaps be 

 open to doubt whether in the very youngest condition the 

 rule is quite absolute. Professor \V. C. Williamson describes 

 the test of OrhicuUna as finely perforated ; Dr. Carpenter, 

 on the other hand, believes the minute dots observable in 

 sections of the shell in either genus to be caused by mere 

 pittings of the surface. It may be that the latter is the 

 correct interpretation, but it is by no means evident that it 

 is so when very young specimens, the tests of which are 

 little more than a film, are examined by transmitted light 

 after one side has been ground off, so that only a single 

 thickness of shell remains. Occasionally the appearance of 

 the numberless dots, even in sections of the adult shell, is 

 much more that of perforations which have been filled up by 

 a subsequent deposit of somewhat different physical charac- 

 ters, than that of mere superficial depressions. Dr. Car- 

 penter's view, however, receives considerable support from 

 Milioline species like QuinquelocuUna punctata, E.euss,t the 

 surface of which, in adult specimens, is represented as 

 regularly pitted. In one of the " Challenger," MilioUncR, 

 characterised by somewhat peculiar surface ornamentation, 

 the old shells are often punctured in regular lines, but this 

 is an accidental circumstance, and depends upon the raised 

 pattern, which leaves the walls very thin and easily worn 

 into holes at certain points, as indicated by the fact that 

 young or otherwise perfect specimei;s are never perforate. 

 1 'Neues Jahrbuch fiir Min.,' for 1853, pi. 9, fig. 8, a—c. 



