DESCRIPTION OF SAMPLES 



47 



benthonic foraminifera present, and a corresponding dif- 

 ference, though of smaller magnitude, in the percentage 

 of CaCOs- The difference between Globigerina oozes of 

 high and of intermediate CaCOs content is particularly 

 marked in the fine sand grades of the mechanically ana- 

 lyzed samples, as may be seen from the plates. In sam- 

 ples having more than 90 per cent calcium carbonate 

 these grades usually consist almost wholly of entire 

 shells of immature pelagic foraminifera, whereas in 

 samples of lower carbonate content they consist largely 

 of broken fragments of larger shells, together with ben- 

 thonic foraminifera. The inverse relation between 

 CaC03 content and amounts of benthonic foraminifera in 

 pelagic sediments does not hold when the relatively low 

 CaCOs content of a sample is owing to dilution by vol- 

 canic or detrital material, nor is it valid in relatively 

 shallow-water sediments such as pteropod oozes. 



Murray and Philippi (1908) noticed in the samples 

 collected by the Valdivia expedition that "es scheint im 

 Globigerina-schlamm offers ein umkristallisierungs- 

 prozess vor sich zu gehen" (p. 154), which affects the 

 shells of pelagic foraminifera. In the Carnegie samples, 

 recrystallization often seems to have occurred in the 

 shells of certain pelagic species, notably Globorotalia 

 tumida. and G. truncatulinoides . Globigerina conglome- 

 rata. G. rotundata . and G. inflata. and Globigerinoides 

 sacculifera and G. conglobata . The shells of these ani- 

 mals ordinarily consist of very small, closely packed 

 crystals, but when recrystallization has apparently taken 

 place, they are formed of separate prismatic calcite 

 crystals varying in length up to 0.05 mm. As is shown 

 in the section on X-ray analysis, the shells of pelagic 

 foraminifera in deep-sea samples, even when only par- 

 tially recrystallized, consist of calcite, and not arago- 

 nite, which forms the skeletons of certain other groups of 

 organisms. Obvious recrystallization is largely con- 

 fined to those samples of intermediate CaC03 content 

 and of high percentage of benthonic foraminifera in which 

 most of the pelagic shells are broken. In the samples in 

 which the CaC03 content is greater than 90 per cent, the 

 shells of pelagic foraminifera, especially immature 

 forms, are usually smooth and polished in appearance. 



Radiolaria . Besides foraminifera, radiolaria are 

 common constituents of siliceous Globigerina oozes and 

 are, of course, the chief constituents of radiolarian 

 oozes. The remains of radiolaria also make up large 

 amounts of the siliceous oozes collected northeast of 

 Japan. 



Sponges . Traces of sponge spicules were found in 

 eyery sample examined, but the abundance of sponge 

 fragments was more or less inversely proportional to 

 the amount of calcium carbonate in the samples and di- 

 rectly proportional to the amounts of other siliceous or- 

 ganic remains. Sample 72 contained an unusually high 

 percentage of sponge fragments. Dr. M. W. de Lauben- 

 fels kindly examined specimens of sponge fragments 

 from 13 samples but was unable, owing to the fragmen- 

 tary nature of the material, to make any definite identi- 

 fications. His report, in tabular form, is given in table 

 6 (p. 54). 



Echinoids . The presence of minor amounts of echi- 

 noid spines is recorded from twenty-three samples, all 

 but three of which are Globigerina oozes from the south 

 Pacific, and undoubtedly, on careful examination, these 

 remains would be found also in the other Globigerina 

 oozes of the collection. In general, the amounts of echi- 

 noid spines seem to vary directly with the percentages 



of benthonic foraminifera in the samples. Specimens of 

 echinoid spines from samples 14, 17, 18, 25, 27, 29, 31, 

 36, 41, 62, 81, 82, and 85 were sent to Mr. Austin H. 

 Clark for examination. His report is as follows. 



"The echinoid spines are all from deep water 

 spatangoids, some from immature individuals. 



"About twenty species of spatangoids are known 

 from deep water in the Pacific, many, probably most, of 

 which have a very wide distribution. They are all ex- 

 ceedingly delicate. In each individual the spines andpedi- 

 cellariae are very highly diversified. But there is so 

 little that is distinctive about the spines in the several 

 genera concerned that spine fragments cannot be identi- 

 fied with any degree of certainty. 



"As all of these fragments are from secondary or 

 miliary spines, from young spines, or from pedicellar- 

 iae, it is likely that most, if not all, of them came from 

 a more or less considerable distance, and some of them, 

 at least, may be from one or other of the numerous 

 shallow-water species. Had these fragments all been 

 from species living on the bottom where they were found, 

 one would expect to find among them parts of the larger 

 spines and the still more solid spine bosses." 



Bryozoa . Remains of bryozoa have been positively 

 identified in only one sample, no. 15, a Globigerina ooze 

 from the southeast Pacific. Dr. R. S. Sassier identified 

 a small fragment from sample 29 collected from the top 

 of the Merriam Ridge off the South American coast at a 

 depth of 1089 meters, as possibly representing the bry- 

 ozoan genus Retepora . 



Mollusca . Possibly owing to the fact that all the 

 samples were collected from depths greater than 1000 

 meters, the remains of mollusca are very scarce. One 

 or two shells of gastropods were noticed in a few sam- 

 ples. Pteropod remains were only doubtfully recognized. 

 Murray and his co-workers pointed out the virtual ab- 

 sence of pteropod ooze in the Pacific, except for certain 

 small areas near oceanic islands. 



Ostracods . Ostracods are a widely distributed con- 

 stituent of the sediments of the south Pacific, but are al- 

 ways present in very minor amounts, no more than ten 

 individual shells having been seen in any of the fourteen 

 samples in which the presence of ostracods is recorded. 

 These samples range in depth from 1089 to 4693 meters 

 and, with the exception of no. 31, all are Globigerina 

 oozes having carbonate contents ranging between 66 and 

 94 per cent. In general, ostracod shells are most abun- 

 dant in relatively highly calcareous sediments. 



Dr. C. I. Alexander examined specimens of ostra- 

 cods from eleven samples, and was able to identify most 

 of them as belonging to the benthonic genera Cythereis 

 and Krithe. His report, in tabular form, is given in 

 table 7 (p. 55). 



Vertebrate Remains . Although vertebrate remains 

 are said to be rather common in dredgings from the 

 deep-sea areas of the Pacific, they are not common in 

 the Carnegie samples, owing to the method of collection. 

 What appear to be small teeth of fish, however, are of 

 frequent occurrence in all types of samples, being es- 

 pecially noticeable in samples 17, 18, 22, 25, 27, 31, 35, 

 36, 44, 49, 79, and 82 from the south and central Pacific 

 and sample 62 from the north Pacific. Dr. PaulBartsch 

 of the United States National Museum doubts that these 

 are fish teeth. 1 



^Communication to Dr. T. W. Vaughan. 



