Trochiscia moniliformis, E. C. ffl., a forni of Bacillaria. 



By ARTHUR M. EDWARDS, M. D. 



The finding of a form that gives in my supposition the key to 

 « species » warrants me in publishing this paper. I also ask for cri- 

 tisms on the theory. 



Two or three years ago I received from Mr. D. A. Saunders 

 botanist and entomologist of the U. S. Experimental Station, State 

 Agricultural College Brooking, South Dakota a specimen which is 

 labeled : 



D. 1. New Mattakuta, Anette Is. June 99. Salt water. 



The specimen is from Alaska. Attached to the algae in some 

 way presumably by the edge of the valve is Trochiscia moniliformis 

 F. C. M. a Bacillarian. This was first described by Montagne in the 

 Annales des Sciences Naturelles, 20 Ser., Bot, page 349 and figures 

 in Tom. Vili. 



This is a little disc fastened to submerged algae in chains, one 

 to the other, locking like a number of saucers placed in sudi a 

 manner so as to form when viewed on the front view, or E. V. as 

 it is called a number of flattened spheres. 



This has been described by various observers as Cyclotella sco- 

 tica of F. T. Kùtzing, 1844, Bacillarien, page 5o, Taf. I, Fig. II— I II, 

 who found it on Callithamnion and Conferva on the coast of Sco- 

 tland and did not recognize it as Trochiscia moniliformis. It was ho- 

 wer found by Montagne at Callao, in Perù. Kùtzing we see gives 

 it another name but it is the same as the figures show. Kùtzing says 

 that Trochiscia moniliformis is Podosira hormoides F. T. K. and gives 

 it as synonymous with Melosira hormoides, Montagne Fior. Boliv. 

 (1839) p. 2. He also says that it is the same as Podosira nummuloi- 

 des, C. G. E. Abhandl. d. Ber. Ac. 1840. Amer. 1843, Taf. I. III. Fig. 34, 



