POLYSTOMELLINAE 435 



characterized by the large number of chambers (14-16) visible in the final convolution, 

 and a thick rounded edge, but they have a rather sunken umbilicus marked by granula- 

 tions instead of the umbilical boss indicated by Fichtel and Moll. The chambers are 

 inflated and the sutures depressed. When the shell is glassy, the light on the highest 

 points of the chambers gives a false impresion of stellate limbation to the test. 



Very similar specimens occur in British material, and have usually been recorded as 

 A'', asterizons. The Falkland specimens of A^. asterisaiis, however, present so many 

 differences that we have thought it desirable to separate them. Fichtel and Moll's name 

 has been little used, but is the geno-holotype of N onion. 



399. Nonion depressulum (Walker and Jacob). 



Nautilus depressuhis. Walker and Jacob, 1798, AEM, p. 641, pi. xiv, fig. 33. 

 Nonionina dcpressula, Brady, 1884, FC, p. 725, pi. cix, figs. 6, 7. 

 Nonionina depressula. Chapman, 1914, FORS, p. 70, pi. v, fig. 41. 



Fourteen stations: 48, 51, 228, 235, 388; WS 88, 90, 92, 221, 245, 248, 408, 409, 433. 



The specimens are often numerous but never very large, nor are they particularly 

 typical. They are generally small and pauperate, the best being at WS 88. Very good 

 also at WS 408, but here they are small though typical. There is as usual considerable 

 variation, especially in the direction of A^. stelligera, many of the specimens, especially 

 at WS 92, showing limbate markings at the umbilicus. 



400. Nonion asterizans (Fichtel and Moll). 



Nautilus asterizans, Fichtel and Moll, 1798, TM, p. 37, pi. iii, figs. e-h. 



Polystomella crispa var. (Nonionina) asterizans, Parker and Jones, 1865, NAAF, p. 403, pi. xiv, 



fig- 35; Ph xvii, fig. 54. 



Nonionina asterizajis, Heron-Allen and Earland, 1913, CI, p. 143, pi. xiii, figs. 12, 13. 



Six stations: 51 ; WS 83, 88, 90, 93, 408. 



Never very common and, as with all the genus, the specimens are as a rule small. 

 Good and typical specimens at WS 88 and 93. 



401. Nonion umbilicatulum (Walker and Jacob). 



Nautilus umbilicatulus, W^alker and Jacob, 1798, AEAI, p. 641, pi. xiv, fig. 34. 

 Nautilus umbilicatulus, Montagu, 1803-8, TB, p. 191 ; Suppl. p. 78, pi. xviii, fig. 1. 

 Nonionina barleeana, Williamson, 1858, RFGB, p. 32, figs. 68, 69. 

 Nonionina umbilicatula, Terrigi, 1883, CQ, p. 203, pi. iv, fig. 48. 

 Nonion barleeanum, Cushman, 1918, etc., FAO, 1930, p. ii, pi. iv, fig. 5. 



Nine stations: 236; WS 88, 91, 99, 215, 221, 248, 408, 409. 



Rare: all the specimens are very small. The figures of Walker and Jacob, and of 

 Montagu are more or less unrecognizable, but the specific name has become definitely 

 associated with a species very common in northern waters. This species was first 

 admirably illustrated by Williamson {lit supra). 



DIV 19 



