404 Prof. T. E. Jones on Dimorphism in the 



To return to " dimorphism " as treated by Munier-Chalmas 

 and Sclilumber;yer — P. Fischer and G. Dollfus think that the 

 megalospheres* (A) indicate oviparous individuals, and the 

 microspheres (B) those that reproduce by gemmules or by 

 fissiparity. Some think that the two forms should be sepa- 

 rately indicated by a modified specific name, or by a sign, or 

 otherwise. A. Tellini affixes " sub " for the megalospheric 

 form of a species ; but G. Dollfus prefers a contrary arrange- 

 ment. 



The researches of MM. Munier-Chalmas and C. Schlum- 

 berger have gone far to show that the Miliolines can be 

 divided, with ,a certain amount of exactitude, into various 

 " genera " if their internal structure be examined by means 

 of microgcopic sections, and if the differentiation be of suffi- 

 cient zoological value. Not only does the " dimorphism " 

 occur in the many forms examined, but the arrangement and 

 disposition of the chambers follow definite laws and are con- 

 stant. 



The structural differences among the Miliolida3 and others 

 discovered and illustrated by MM. Munier-Chalmas and 

 Schlumberger are of very great interest, adding much to our 

 knowledge of Foraminifera. They are often associated with 

 external features sufficiently recognizable for the use of the 

 trivial names already in vogue, and the zoological standing 

 of the members of the group is not interfered with. Indeed 

 their mutual relationships have strong evidence in the new 

 observations. Thus the structure of Biloculina depressa, form 

 B, shows that this form passes through (1) a biloculine, (2) 

 a triloculine, (3) a quinqueloculine, and (4) a biloculine stage 

 in reaching completion ; whilst B. comata has (1) a biloculine, 

 (2) a quinqueloculine, (3) a quadriloculine, (4) a triloculine, 

 and ultimately (5) a biloculine stage. Adelosina, after its 

 unilocular form, has biloculine, triloculine, quadriloculine, and 

 quinqueloculine stages. The early changes constitute what 

 is termed " Initial Polymorphism " by MM. Munier-Chalmas 

 and Schlumberger. It is apparent that by these and the 

 later changes, all within the agathistegian cycle, not only is 

 the real generic value of Miliolina more firmly established, 

 but that it has a right to include Biloculina and Spiroloculina 

 (as applied by Dr. A. Goes). 



M. Schlumberger states that in the Bilocidince and Tri- 

 Joculinoi having a small initial chamber (the form B) the first 

 chambers are as in Quinquehculina ; subsequent chambers 



* The word " megaspliere/' thus shortened by ellijjsis, is preferred by 

 the authors mentioned. 



