Foraminiferal Limestones. 239 



Amphistegina lessonii, d'Orbigny. 



The specimens of this species are both common and well- 

 <leveloped. Some of the tests are very thick and belong- to the 

 dome-shaped variety, which has been often noticed under separate 

 specific names, from beds of Miocene age. This variety, however, 

 is not confined to fossil deposits, it having been frequently seen in 

 coral-sands of recent times. 



Heterostegina depressa, d'Orbigny, 



This species is here numerous and of ti somewhat peculiar tj'pe, 

 the central portion being much swollen, whilst the flanged portion 

 is not so expansive as in specimens noticed earlier in this paper. 



Limestone No. 220 is the rock from the south side of the basalt 

 mass mentioned, and is entirely different from the preceding 

 specimen. It bears a strong resemblance to No. 924 previously 

 ■described, and there cannot be much doubt that this specimen is 

 an extension of jS^o. 924. 



It is a pale or cream-coloured limestone, full of Orhitoides. 



Seen under the microscope parts of the rock appear somewhat 

 brecciated. The rock is well ciystallized, but nevertheless the 

 organisms are perfectly preserved. 



The rock is composed of a branching Lithothamnion (one specimen 

 of Orhitoides has it growing upon the surface), foraminifera, 

 echinodenn plates, polyzoa, and molluscan shell-fragments. 



The foraminifera arc as follows : — 



Carpenteria, sp. 



This genus is here represented by numerous fragments of the 

 shell -wall, but it is impossible to say to what species it may 

 belong, although it bears the same general characters of the test 

 as C. monticiilaris. 



Gypsina iiihrnrens ? (Schultze). 



There are numerous irregularly grown adherent foraminifera in 

 specimen No. 220 which appear to belong to the above species. 



Gypsina globulus (Eeuss). 

 One specimen in No. 220. 



Polytrema miniaceum (Pallas) and var. involva, Chapman, nov. 



One of the adherent forms of the foraminifera in No. 220 is 

 very similar in structure to the laminar or outspreading forms of 



