1910.] NATURAL SCIENCES OF PHILADELPHIA. 457 



to me is Mr. Terry's own account 3 of its discovery on Fall Mountain 

 with some reference to the very odd features of the upper valve. 



During July of 1909 I received from Mr. Terry sundry vials of 

 diatoms collected on Fall Mountain in 1891, with a request for the 

 preparation of a number of arranged mounts, each of which was to 

 show the upper valve, the lower valve and the complete frustule of 

 Stauroneis terryi. Some of this material was labelled "fossil" and 

 some " recent." It consisted very largely of Stauroneis acuta, together 

 with its varieties, among which one might easily imagine " var. terryana, 

 Tempere." But the diatom so tardy in the matter of obtaining 

 recognition, though present merely in traces, was in such marked 

 contrast with all these that no special difficulty was experienced in 

 culling it from its multitudinous associates. During the preparation 

 of the slides a certain curious or even unprecedented feature was 

 noticed in many of the intact frustules — a feature neither shown by 

 Dr. Ward's preparations and photographs, nor mentioned in any 

 previous reference to this diatom. This was brought to Mr. Terry's 

 attention, and at his request I have had proper illustrations made of 

 the whole form, and present the following description of the diatom. 



Stauroneis terryi D. B. Ward (ined.)- 



Frustule fusiform, slightly arcuate in girdle view, the upper valve 

 more convex than the lower. Valves dissimilar, the upper partly 

 enclosing the lower. No girdle bands, the valves held in place by a 

 broad external silicious ring at the middle part. Ring slightly 

 cemented to the valves, easily detached, about one-eighth the length 

 of the frustule, very thin, surface obscurely punctate. Upper valve 

 370-400 u long, 55-60 a broad. Strongly convex transversely, swollen 

 at the middle, diminishing with concave outlines to long, bluntly 

 rounded apices, and bearing a large oval depression toward each end 

 wherein the raphe terminates in a fine waved line; axial hyaline area 

 rectilinear, expanding spatulately around subterminal depressions. 

 Lower valve slightly smaller in all dimensions, without subterminal 

 depressions, apices more slender, with lumen formed by a conspicuous 

 thickening of the inner terminal margin; raphe continued approxi- 

 mately to end of valve; hyaline area rectilinear to the lumen, then nar- 

 rowing almost to a point. Stauros on both valves widening outward. 

 Striae 12 in 10 //, nearly normal to periphery throughout, punctse 

 becoming coarser and striae more sparse around ends of upper valve. 



3 W. A. Terrv, -4 Partial List of Connecticut Diatoms, Rhodora, August, 1907, 

 p. 126. 



