I04 DISCOVERY REPORTS 



very rare. I know of no other record, and its occurrence in such numbers at a few 

 stations in the Antarctic is an interesting problem of distribution. 



The specimens appear to comply almost exactly both with the figure and description 

 of Goes, but are more solidly constructed, a good deal of ferruginous cement being 

 employed, and there is a very slight umbilical depression. The original description is as 

 follows (translation) : Test trochoid and subglobose, very thin, five to seven convolutions, 

 about five chambers in the last convolution, half-embracing, inflated; oral face not 

 umbilicate. Pale rusty or yellowish colour, translucent. Diameter 0-40 mm. 



203. Trochammina conica, sp.n. (Plate III, figs. 47-49). 

 Two stations: 200; WS 517. 



Test conical ; dorsal side exhibiting all convolutions, four or five in number, each of 

 three chambers inflated and rapidly increasing in size ; sutures depressed. Ventral side 

 showing only the three chambers of the final convolution which are very inflated ; deeply 

 excavated at the umbilicus. Aperture a small arch in the middle of the inner face of the 

 final chamber. Composed of rather coarse sand grains and cement, surface neatly 

 finished but not smooth. Colour deep red or brown at apex, lighter towards the last 

 chambers. 



Diameter about 0-2 mm.; height about the same. Two specimens at St. WS 517 in 

 2770 m., and one at St. 200 in 345 m., somewhat rougher in construction. 



This little species has considerable resemblance to Valvulina conica, and bears the 

 same relation to that species that Trochammina squamata does to Valvulina fusca. It is 

 distinguishable by its aperture and minute size. 



204. Trochammina discorbis, sp.n. (Plate III, figs. 28-31). 

 Three stations: 360; WS 471, 516. 



Test free, minute, a trochoid spiral of 3-4 convolutions, with five or sometimes only 

 four chambers in the final convolution. Dorsal surface highly convex, exhibiting all 

 convolutions, which are slightly "stepped" one below another. Ventral surface nearly 

 flat but with a deeply sunk umbilicus, exhibiting only the chambers of the final convolu- 

 tion. Sutural lines recurved on dorsal side, straight on ventral, slightly depressed. 

 Peripheral edge subacute. Aperture a small slit on inner edge of final chamber on 

 ventral side. Constructed of very fine sand with much cement. Colour dark ferruginous 

 brown, sometimes nearly black, but occasionally lighter. Surface smooth but not highly 

 polished. 



Breadth up to 0-2 mm. ; height about 0-07 mm. 



This pretty little species is an almost perfect isomorph of some of the smaller forms 

 oi Discorbis of the D. rosaceiis group. The few records are in deep water, 261 1-3264 m., in 

 the Scotia and Bellingshausen Seas, and widely separated. A good many specimens 

 were found at St. 360 but only single individuals at the other stations. 



Egger (E. 1893, FG, p. 264, pi. v, figs. 19-21, 48-52) describes and figures a little 

 species, Trochammina plana, which bears some resemblance to my species, having five 

 chambers in the convolution and a flat ventral surface with sunken umbilicus. But the 



