346 



Description of a New Species of Fabularia. 



By M. C. Schlumberger. 



(Communicated by Walter Howchin, F.G.8.) 



[Read October 6, 1891.] 



Plate XTII., figs. 5-8. 



A few months ago I received from Mr. Sherborn, of London, 

 several Foraminifera discovered by Mr. Howchin"^ in the 

 Miocene beds of Muddy Creek, Victoria. Two of them 

 seemed to be Biloculiiim with large longitudinal costal and a 

 cribriform aperture. These characters were remarkable enough, 

 inasmuch as all known sjDecies of Bilocidina, except B. comata, 

 Brady, are smooth, and have a single tooth in the oral aperture. 

 It was an easy matter to mistake the generic relationships of the 

 specimens, as they were much weathered. Happily, Mr. Howchin 

 obtained other specimens and kindly forwarded them to me. 

 They are true Fahidaria, and their discovery in a fresh locality 

 is of the greatest interest, as the genus is only known by a single 

 species from the Eocene (Calcaire gi'ossier) of Paris and Egypt. 



Two of the five specimens sent are sufficiently complete to 

 allow a recognition of the external characters, and furnish 

 material for a o'ood drawing. The other three were used for the 

 execution of two transverse and a longitudinal section. They all 

 belong to the Form B,t whilst the Form A remains to be dis- 



* The objects referred to by Mr. Schlumberger are the same as were 

 briefly noted by me in " The Foraminifera of the Older Tertiary of Muddy 

 Creek" as Bilocidina species (Trans. Roy. Soc. S. Aus., vol. XII., p. 1), 

 and which at the time of publication had been mislaid after having been 

 submitted to the late Dr. H. B. Brady. The weathered condition of the 

 test, added to the extraordinary external resemblance which this interest- 

 ing object bears to the genus Bilocidina, misled Dr. Brady, as it did Mr. 

 Schlumberger in the first instance, and it was only on my making a section 

 of the object that its true generic relationship was made apparent. — 

 W. HOWCHIX. 



t Interesting researches, bearing on the internal structure of the Foram- 

 inifera, made by the eminent specialists, MM. Munier-Chalmas and C. 

 Schlumberger, have established the fact that many Foraminifera, notably 

 Niimmulites and the Miliolidae, possess a dimorphic structure in their 

 respective species. The dimorphism is of a similar kind in all the genera 

 and species which exhibit the phenomenon, and determines the size and 

 arrangement of the initial chambers. The authors referred to above dis- 

 tinguish the dimorphic types as Form A and Form B. The former pos- 

 sesses, relatively, a very large initial chamber, whilst in the latter the 

 initial chamber is small, and is surrounded by numerous small and gradu- 

 ally enlargmg chambers.— W. Howchin. 



