POLYSTOMELLINAE 439 



At this Station, which is just on the edge of the Continental Shelf between the Falkland 

 Islands and the Straits of Magellan, a single specimen was found which appears to agree 

 with the figure and description of A^. chiliensis, recently described from the Chilean 

 coast. The specimen is a dead and worn shell and may have drifted a long way. The 

 specimen measures 0-65 mm. in breadth, and 0-55 mm. in width. 



The authors remark that " at first glance this might not be thought to be a Nonionella ". 

 With this we agree, but in the absence of further material are not prepared to question 

 the assignment. 



Genus Elphidium, Montfort, 1808 



412. Elphidium (Polystomella) incertum (Williamson) (Plate XVI, figs. 20, 21). 

 Polystomella umbilicattda var. iiicerta, Williamson, 1858, RFGB, p. 44, fig. 82 a. 

 Polystomella decipietis, Heron-Allen and Earland {nan Costaj, 1916, FWS, p. 282, pi. xliii, 

 figs. 20-22. 



Elphidium incertutn, Cushman, 1918, etc., FAO, 1930, p. 18, pi. vii, figs. 4-9. 



Four stations: 51 ; WS 86, 89, 90. 



Williamson's variety (P. umbilicatula var. incerta) which, in the absence of any speci- 

 mens of the typical P. striato-puiiclata (Fichtell and Moll), may claim the earliest name 

 for the cooler water types so generally assigned to Fichtel and Moll's species, is by no 

 means common in this material compared with its abundance in northern waters, but 

 excellent specimens in considerable numbers occur at WS 89 and 90. 



413. Elphidium (Polystomella) excavatum (Terquem) (Plate XVI, figs. 22, 23). 



Polystomella umbilicatula, Williamson {non W. & J.), 1858, RFGB, p. 42, fig. 81. 

 Polystomella excavata, Terquem, 1875, etc., APD, 1875, p. 25, pi. ii, fig. 2. 

 Elphidium excavatum, Cushman, 1918, etc., FAO, 1930, p. 21, pi. viii, figs. 1-7. 



Two stations: WS 89, 92. 



Under this name Terquem separated the very common northern type which William- 

 son had earlier figured admirably under the erroneous designation P. umbilicatula, 

 Walker (and Boys). The specimens are curiously rare in the Falkland Islands material, 

 probably owing to the water being of too high a salinity. On the British Coasts, the 

 species reaches its maximum development in numbers and size under estuarine con- 

 ditions. 



414. Elphidium (Polystomella) articulatum (d'Orbigny). 



Polystomella articulata, d'Orbigny, 1839, FAM, p. 30, pi. iii, figs. 9, 10. 

 Elphidium articulatum, Cushman, 1918, etc., FAO, 1930, p. 26, pi. x, figs. 6-8. 

 Three stations: 51, 235; WS 217. 



This species, recorded by d'Orbigny from the Falkland Islands, is rare in our material, 

 probably on account of the too great depth, as Cushman reports it as being common in 

 the shallow water gatherings made by Dr Waldo Schmitt in the same area. The Type in 

 Paris appears to have been transposed. The tube labelled P. articulata contains only a 

 single specimen covered with efflorescence ; when this was removed by careful washing, 



