Recent and Fossil Foraminifera. olio 



by Mr. H. F. Angus, and the observations recorded. In September, 

 the number of shells in the tanks having greatly increased (though 

 we must confess that we have never been able to observe the 

 actual processes of reproduction), we washed out the contents of 

 two of the tanks for examination. We were astonished to find 

 that the majority of the shells of Massilina seams, the principal 

 denizen of our tanks, were more or less distorted or idiosyncratic. 

 Among the dried and floated shells we found all three of the 

 varietal forms above described, and not only was this the case, 

 but we found them in extraordinary combinations : var. denticulata 

 also tenuistriata, var. tenuistriata also obliquistriata, and there 

 is one shell on the slide exhibited this evening which exhibits 

 all three variations, so that it might be referred to as Massilina 

 secans, var. denticulata-tenuistriata-obliquistriata d'Orbigny-Costa- 

 Earland-Halkyard ! 



It must be borne in mind that these shells were grown under 

 peculiarly starved conditions. The tanks measure on an average 

 5 in. by 6 in. in height and breadth, and have a diameter from 

 back to front of only f in. It is therefore obvious that the supply 

 of carbonate of lime and other salts at the disposal of the Foramini- 

 fera born in the tanks is very limited, for it must be remembered 

 that these observations have been carried on in London, and the 

 sea-water has never been renewed. It has been kept sweet by the 

 growth of green alga;, which oxygenate the water, and evaporation 

 has been compensated by the addition of fresh-water from time to 

 time when the specific gravity bulbs warned us of increasing 

 salinity. 



We are therefore led to the conclusion that these varietal 

 markings, in Massilina at any rate, are nothing more than the effect 

 of the animal having to live under starved and unnatural con- 

 ditions, and it will be interesting to see whether the same tendency 

 to variation will be exhibited by other species grown under similar 

 conditions. 



The curious monstrous forms, of which a number of specimens 

 are exhibited, are usually the result of damage. It is difficult to sur- 

 mise to what dangers of damage Massilina may be exposed when 

 clinging to rocks or algse, but it seems indifferent to casualties. 

 We have frequently, in the attempt to dislodge a shell for closer 

 examination, smashed the ultimate or penultimate chamber. In 

 the former case the pseudopodia were soon extended from the 

 point of fracture, and in the latter from the end of what would 

 have been the last chamber if its growth had been checked at that 

 point, and it is a common thing to find a Massilina whose shell has 

 been broken, repaired by the secretion of a new shell over the 

 protoplasm protruded at the point of fracture. 



