444 PERCY SLADEN TRUST EXPEDITION 



This led me to test the provisional hypothesis that the specimens examined by 

 Carpenter and those examined by some of the other observers belong to quite distinct 

 genera. I therefore searched through all the many bottles of Corals, Alcyonaria and other 

 specimens of marine fauna in the laboratory and examined any red patches I could find 

 that had the least resemblance to a Polytrema; and I also examined a large number of 

 specimens of the genus in the collections at the British Museum. 



The result was to prove conclusively that there are at least two distinct genera of 

 Foraminifera included in the group of specimens which are usually labelled in Museums 

 " Polytrema miniaceum" and that these two genera differ from one another by constant 

 and well defined characters. For the form that is certainly common in the Mediterranean 

 Sea but is also widely distributed in other parts of the world I propose to retain the generic 

 name Polytrema, for the other genus which does not, so far as my information goes at 

 present, occur in the Mediterranean Sea at all, I propose the new generic name Homotrema. 



But to return to the specimens identified as Polytrema cylindricum. A critical 

 examination of my own specimens proved that their structure was in many respects quite 

 distinct from that of either Polytrema or Homotrema, and having convinced myself that 

 they are not gross, overgrown or hypertrophied specimens of either of these two genera 

 I propose now to constitute for them a new generic name Sporadotrema. 



I wish to acknowledge the assistance I have received in the course of this investigation 

 from Mr H. Sidebottom, a well-known authority on the Foraminifera, and from Professor 

 Burrows of the Manchester University whose advice I have followed in the construction 

 of the new generic names. 



I am also indebted to the authorities of the Free Public Museum at Liverpool for the 

 loan of the type specimens of Sporadotrema cylindricum and to Mr Kirkpatrick for his 

 assistance in my study of the specimens of Polytrema in the British Museum. 



The very fine set of specimens and preparations of the genus Polytrema made by 

 Mr E. Halkyard which was recently presented to the Manchester Museum with the rest 

 of his rich collection of Foraminifera has been of invaluable assistance to me in the study 

 of the genus. 



II. DIAGNOSES OF THE THREE GENERA. 

 1. Polytrema. 



The original description of this genus given by Pallas (14) is as follows : 



Millepora miniacea — M. pumila subramosa rubra, punctis crebris impressis minutis. 

 Maris Mediterranei, Americani, Indicique Corallia. 



Tournefort* committed himself to the view that this coral was the beginning of the 

 true red coral, i.e. Corallium. It was Risso, in 1826, who separated it from the genus 

 Millepora, but Dujardin, in 1841, first placed it tentatively among the Rhizopoda. 



Coming down to more recent times the more important papers on the genus are by 

 Max Schultze (15), Mobius (13), Carter (3) and Merkel (12). 



* Mem. Acad. Sci. 1700, p. 35. 



