424 



KNOWLEDGE. 



November, 1910. 



Haplophraf^iiiiinn. They cra\\led up the sides of 

 the tanks, clini;ing to the glass and to the weed- 

 grown rocks placed in the tanks, h_\- their pseudo- 

 podia which extended in all directions from the 

 aperture. In these early days their appearance was 

 magnificent. Like the large specimens of Venie- 

 niliiHT polysfropha which constitute a feature of 

 the sand and mud of the Mixon Reef, these 

 Haplophra^niiii appear to be endowed — one says it 

 with all reservation — with an aesthetic sense. 

 Unlike, or at any rate to a much more marked 

 degree than, the specimens of the same species 



found among shore gathering 



the immediate 



neighbourhood, these Haploplinjginia and Veriie- 

 iiiliiiae deliberatel\- sefect for the construction of their 

 shells large fragments of finely coloured quart/, 

 garnets, chips of magnetite and coal, glauconite, and 

 particularK' of an unidentified gem mineral which 

 is found in the detritus of the Alveolina lime-stone 

 rocks which form the Mixon Reef. The result is a 

 shell built up of shining blocks of black. yellov\-, 

 crimson, brown and green, of a peculiarly splendid 

 appearance. 



In the course of weeks and months, whilst the 

 commoner forms continued to flourish and increased 

 in numbers, most of these beautiful Haplophra^inia 

 disappeared, though two or three fine specimens still 

 (September) make their appearance at intervals. 

 In two of our tanks in which, owing to the 

 death of larger organisms, the layer of mud 

 putrified, the Haplopliraiiinia turned black, antl fell 

 to pieces when fished out of the tank. When the 

 tanks were cleared out there was no trace of them. 

 At the end of some months we decided to wash and 

 examine the layers of clean mud which had lined the 

 bottoms of three other tanks — it must be borne in 

 mind that this material had never formed part of any 

 sea bottom but was washed clean from the fronds of 

 the .Mga. It was carefully washed on a silk sieve 

 and dried by very gentle sun-heat with a view to its 

 being '" floated '" to separate the Foraminifera. Before 

 this was done, however, \\e examined the dried 

 material, and \se were astonished to find that on the 

 sieve which retained the medium siftings the perfect 

 shells of Haplophragmiiiin agi^liifiiians iormed 20/;'i of 

 the washed (not floated) material. I'Vom this material 

 the shells represented in Figure 1 were picked. The 

 material was then heated, cooled, and floated 

 in the usual manner and we were provided with 

 a fresh surprise. name!\-, that in the floatings 

 Hdplophrai^iniuin iii^i^liitiiums was quite as rare as it 

 ever is in a shore gathering. We are therefore 

 justified in assuming that the species may be a 

 common one in gatherings of living Foraminifera 

 from .\lgae, and that the shell is constructed with a 

 peculiarlv perishable cement which conduces to its 

 disintegration under the action of the waves upon 



the shore and the processes of drying and floating. 

 On this assumption we ma\- infer that the rare 

 individuals found in shore gatherings are those 

 which ha\e been washed up alive by the last tide 

 and have been held together by their contained 

 sarcode. 



In this fragility it entirely differs from our other 

 species Haplophmgmiitm canariense, which is solidh- 

 built, smooth and robust, and sur\ives the most heroic 

 treatment. 



[We take this opportunity of recording that the 

 mud obtained from these tanks contained many fine 

 and t\pical specimens of Massiliiia secans var. 

 denticulata Costa in which the final chamber has a 

 delicate serrate carina. This variety has only been 

 recorded previously in Britain from the neighbouring 

 locality of Bognor*. There were also many specimens 

 of Massilina sccaiis in which the two final chambers 

 showed deep median constrictions, resembling septal 

 divisions, somewhat like the specimens for which 

 Halkyard proposed the varietal name ohlicjiiisfriata, 

 subsequentlv withdrawn by the same author, and also 

 of Earland's variety (loc. c7b.) feniiisfriataj 



As none of these curious varieties were observed 

 either in the fresh gatherings which we made at the 

 Mixon Beacon, or in any of the numerous shore 

 gatherings made at Selse_\- over a long period and 

 wide area, we are forced to the conclusion that they 

 are the result of starved or unfavourable conditions 

 of life in a confined tank reacting on the shell- 

 secreting powers of the species in question.] 



Our second species Haplopliragmiuin canariense 

 possesses little in common with H. agghitinans. It 

 is, as will be seen from our Figure 2, a regularly 

 nautiloid shell, consisting of several convolutions, 

 the outermost having from six to nine segments. 

 The convolutions are embracing, so that the last 

 whorl entirelv, or almost entirely, includes its prede- 

 cessors. The lateral surfaces sink towards the 

 umbilical depression w hich is more or less excavated. 

 The peripheral edge is rounded and more or less 

 lobed. The aperture is a thin slit set on the face of 

 the last segment close to the inner margin, and 

 sometimes surrounded by a lip. The surface of 

 shore specimens is usually smooth and neatlv 

 finished, the wall being built up of fine sand grains 

 cemented together with a ferruginous secretion 

 which gives a delicate rust colour to the ^\•hole shell. 

 The colour, which depends on the cement, is, however, 

 rather variable, ranging from deep brown to light 

 grev. and the earlier segments are generally' darker 

 than the later ones. 



The shell-wall in shore specimens is always thin 

 and nearly smooth, but in deeper water the animal 

 uses larger sand-grains so that the surface becomes 

 somewhat rough. In certain localities, notably the 



'■'■Earland A. The Foraminifera of the Shore sand at Bognor, Sussex. Joiinutl Oitckctt Micro. C!i(b. 1905, ser. 2, vol. ix.. 



No. 57, p. 198, pi. xi, fig. 4. 



*^Siginoilifia sccaiis var. ubliquist nata. Halkyard, 1889, Trans. Manchester Micr. Soc., p. 61, pi. i, fig. 7. This variety was 



subsequently withdrawn by Halfivard in Trans. Manchester Mic. Soc., 1891, p. 20. 



