REPORT ON MATERIALS PROM THE BORINGS AT FUNAFUTI ATOLL. 261 



cemented by crystalline dolomite. There is hardly a trace of a coral to be seen on 

 the slit surfaces of the cores, but there are good reasons for regarding the cavernous 

 hollows as having originally been occupied by corals, and in addition to these, the 

 cores contain portions of solid crystalline material, mostly without structure, which 

 likewise were probably at first corals, which have now been altered and replaced 

 by the secondary crystallisation. In microscopic sections the crystalline portions can 

 be seen with traces of coral casts in them, and they are often surrounded by layers 

 of Polytrema and Lithothamnion, which originally grew over the corals. In the 

 lower cores, corals, belonging to Astrcea, are largely developed. 



Foraminifera are generally present ; the commoner forms are Polytrema and 

 Amphistegina, and they are pretty well the only ones recognisable with a lens ; in 

 microscopic sections the following genera are also shown : — -Orhitolites, Peneroplis, 

 Bolivina, Glohigerina, Planorhtdina, Carpenteria, Gypsina and Heterostegina. 

 Echinid spines are numerous, alcyonarian spicules, and Leptoclinwrn stellates, 

 LitlwthawAiion. • 



Details. 



(249a). Length 90 millims. Whitish-grey, mottled, hard, mostly compact. Trace of perforate coral. 

 Nearly altogether detrital, with Pohjtrema, Amphistegina and echinid spines. 



(250a) [750]. Length 223 millims. AVhitish-grey, mottled, partly porous, partly compact; occasional 

 cavities. The core consists of consolidated organic sediment, with numerous foraminifera belonging to 

 Peneroplis, Glohigerina, Planorbulina, Carpenteria, Gypsina inhcerens, Polytrema miniaceum, P. planvm, 

 Amphistegina, and Heterostegina. Echinid spines. 



(251a). Length 248 millims. Whitish-grej'-, hard, mostly compact, with occasional hollows. The 

 greater part of detrital materials with Amphistegina. Alcyonarian spicules. Echinid spines. 



(252a-255a). Total length 352 millims. Cylindrical cores of whitish-grey, hard, generally compact, 

 .dolomite, with caA'ities lined with the crystalline deposit; the same material also fills up areas in the 

 cores where corals have been present. Mostly of detrital sediment with foraminifera and echinid spines. 



(256a, 257a). Total length 270 millims. Cores of the same whitish-grey rock as the preceding, very 

 cavernous in places, in section showing a large infilling of the banded agate-like crystalline deposit. 

 Only echinid spines to be seen with a lens. 



(258a) [751]. Length 97 millims. Whitish, hard, compact to porous, with some cavities. Traces of 

 Coral. Core nearly altogether of fine organic sediment, but becoming crystalline. The foraminifera shown 

 in a microscopic section belong to Orhitolites, Glohigerina, Planorbulina, Carpenteria, and Polytrema planiim. 

 Alcyonarian spicules and echinid spines. Casts of Leptodimim stellates. 



(259a). Length 90 millims. Grey and white areas, the latter poroi;s and not so hard as the grey 

 portions. Only echinid spines recognisable under a lens. 



(260a). Length 160 millims. About half the core greyish, hard, crystalline, with cast of perforate 

 coral, C?) Astrceopwa, the other part of the core whitish, efflorescent, porous, apparently of detrital sediment 

 with echinid spines. 



(261a). Length 128 millims. Principally whitish, speckled, moderately hard, porous dolomite, 

 efflorescent ; in the lower portion greyish, crystaUine, with traces of perforate coral. The white part of 

 the core of detrital materials, with echinid spines and casts of small gastropods. LitJwtJuimnion. 



(262a). Length 104 millims. Core of grey and white portions irregularly intermingled; large hollow 

 lined by crystalline deposit. Casts of small perforate corals. Echinid spines numerous. Orhitolites. 



(263a). Length 86 millims. Greyish-white, hard, with numerous small hollows from which organisms 



