310 Miscellaneous. 



MISCELLANEOUS. 



On tlie Mineralogical Structure of the PorceJlanous Foraminifera. 



To the Editors of the '■Annals and Magazine of Natural Hlstonj' 



Gentlkmex, — In Mr. J. J. Lister's work on the Foraminifera 

 (' Treatise on Zoology,' pt. i.), a copy of which I have only just seen, 

 that author has put a misconstruction on m}- statements regarding 

 the probable mineralogical structure of the porcellanous Foramini- 

 fera. On p. 54 he says, " Chapman also has recently stated that 

 the tests of the Miliolidea are of aragonite, or, rather (following 

 Miss Kelly, 'Mineralogical Magazine,' vol. xii. (1900) p. 363), 

 conchite. I am inclined to doubt this conclusion." If Mr. Lister 

 will kindly turn to p. 39 of my work on the Foraminifera, he wiU 

 there read, " The mineral constituent of this type has long been 

 supposed to be carbonate of lime in the form of aragonite. This 

 appears from recent researches and from the author's own experi- 

 ments to be extremely doubtful, and is more likely to be an inter- 

 mediate mineral condition in which the organic element is intimately 

 mixed with the mineral, and probably corresponding with the new 

 mineral species Conchite, One powerful argument against the view 

 that the porcellanous shell is composed of aragonite, which is a very 

 unstable mineral, is the fact that certain calcareo-argillaceous rocks 

 of Carbo-Permian age from Australia have recently been described 

 which are largely made up of the tests of a wild-growing or 

 meandering form of NuhecuJaria in which the shell-texture is 

 exactly comparable with that of the recent porcellanous forms of 

 the genus." 



Incidentally I may mention that the optical phenomena exhibited 

 by thin slices of porcellanous Foraminifera are not in favour of 

 their being formed of calcite, as Mr. Lister supposes, as I have 

 repeatedly observed traces of anomalous biaxial figures under 

 convergent polarized light. 



Fredeeick Chapman. 



National Museum, Melbourne, Australia. 

 August 10th, 1904. 



The Limacodid Lepidoptera and their Dipterous Parasites, Bomhij- 

 lides of the Genus Systropus : Parallel Adaptation of Host and 

 Parasite to the same Conditions of Existence. By J. Kunckel 

 d'Heectjlais. 



In the course of the mission which I have fulfilled in the 

 Argentine Eepublic (1898-1900) I had an opportunity of observing 

 the singular organic likeness between the Lepidopterous host and 



