DISTRIBUTION: Known for certain from the Ross Sea and off Enderby Land on the antarctic continent but probably much more widely distributed. Also recorded from the Antarctic Peninsula, South Shetlands, South Orkneys, South Sandwich Islands, South Georgia, Shag Rocks, the Burdwood Bank, Falkland Islands and off Tierra del Fuego. The known bathymetric range is 183-1674 m, from which depths it has been recorded from the Ross Sea.

REMARKS: The writer (Dell, 1964a: 229) suggested that G. plicata Thiele was probably based upon a juvenile specimen of C. tenella. The additional material of tenella examined more recently has confirmed this conclusion. In this paper tenella is interpreted as the large (up to 45 mm in length) form that agrees with the holotype and the specimen figured by the writer (Dell, 1964a: pl.7, fig. 13). The specimens from the Magellanic region compare very closely with those from antarctic waters and from off South Georgia. Specimens from Eltanin Stn 558 range from 21.3 to 37.5 mm in length and thus supply useful information on growth stages. The largest Magellanic specimen (Eltanin Stn 740) is 43.3 mm long.

The distinguishing characters of C. tenella are its comparatively large size, comparatively short, wide rostrum and fairly closely spaced, strong, but irregular commarginal sculpture.