508 C. CLIFFOED DOBELL. 



tlie Spiroclitets are allied to the flagellate Protozoa ; many 

 considei' that their proper systematic position is among the 

 Bacteria. As I have devoted a considerable amount of study 

 to both these groups — as regards their cytology and liFe- 

 histories — I have naturally been anxious to extend my studies 

 to the Spirochaets. The present paper represents a part of 

 the researches which I have made upon these organisms, 

 with the conclusions derived from them. I may state at the 

 outset that my own observations have led me to believe that 

 the Spirochtets are really neither Protozoa nor Bacteria, but 

 a group of Protista which — for the present — must be held to 

 stand apart. 



In the present paper I shall describe some researches 

 which I made upon the Spirocha3ts of Molluscs — to one species 

 of which I have devoted special attention. With the 

 exception of the work of Schellack (1909) and Gross (1910), 

 almost all the observations which have been made upon these 

 forms are, I believe, marred b}^ incorrect interpretation. 

 My own observations and interpretations — made quite inde- 

 pendently, and upon different material — correspond in many 

 ways with those of Schellack and Gross. 



1 shall adopt the generic name Cristispira Gross to 

 denote the flexible, spiral organisms which occur in the 

 crystalline styles of so many Lamellibrauchs. It is obvious 

 that the name "S pirocha3ta," which has now for some 

 time been applied to them, is no longer applicable (see p. 5o4). 



Material and Methods. 



The organism with which the present paper is chiefly 

 concerned is a large species of Cristispira which inhabits 

 the crystalline style of Venus (Meretrix) casta Chem. 

 As no Cristispira has previously been recorded from this 

 mollusc, I propose to name the new organism Cristispira 

 veneris n. sp. 



The discovery of this organism is due to Dr. Arthur 

 AVilley, F.R.S., who called my attention to it when I was 



