384 J. WILFRID JACKSON ON 
possessing fine, and others coarse, ribbing. In some cases the ribbing is almost 
entirely obsolete, even in adult examples, a feature already noted by FiscHer and 
OEHLERT, and described and figured by them as var. submutica (1892, p. 279, pl. xi. 
figs. 5-6). 
Internally the specimens present many interesting features. In some examples 
indications of senile conditions:are very apparent. The teeth of the ventral valve 
show considerable enlargement, the muscular impressions are remarkably deep, and the 
peduncular passage is considerably narrowed by thick deposits of calcareous matter on 
either side, forming a deep and narrow channel. The foramen is reduced to a very 
small size (Pl. II. fig. 11). 
In no case, however, are the deltidial plates absorbed, as is often the case during 
senile decay. 
In the dorsal valve similar conditions are to be seen. Here the cardinal process is 
of notable size and the brachial support of extreme tenuity. (See Fiscuer and OnHLERT, 
1892, pl. ix. fic. 6): 
Similar evidences of senility are present externally in the thickening of the lateral 
and frontal margins and the crowding together of the growth lines (PI. II. fig. 12). 
(See also FiscHeR and OEHLERT, 1892, pl. ix. figs. 3-4.) 
The various young examples of this species, obtained mostly from the tests of 
Cephalodiscus, range in size from 1 to 6 mm. and show an interesting series of growth- 
stages in the brachial support. This feature has already been very ably described by 
FiscHER and OEHLERT (1892), and as the above specimens exhibit no important points 
of difference, it will not be necessary to deal with them again here. 
Terebratella dorsata appears to be restricted to the immediate neighbourhood of 
South America. It is an abundant species in the Magellan Straits, the littoral of Tierra 
del Fuego, and Falkland Islands. On the east coast of Patagonia it does not appear 
to range further north than latitude 52° 8. (near Cape Virgins) and the Falkland 
Islands. On the West Patagonian coast it seems to possess a more considerable 
extension, having been recorded from Valparaiso and Coquimbo, Chili. 
A more distant locality has been recorded for this species by Davipson (‘‘ Chall.” 
Report, p. 44), viz. Royal Sound, Kerguelen, but BLocuMann (1906), from a study of 
the original examples, has shown this record to be erroneous, the specimens in question 
being an entirely new species, Terebratella enzenspergerr, Blochmann. 
The bathymetric range of 7. dorsata, according to recent authorities, is from about 
5 to 120 fathoms. 
In the report on the fossil Brachiopoda of the Swedish 8.-P. Expedition, Buckman 
(1910) has described a new species of Magasella (M. antarctica) which appears to 
me to present certain definite resemblances to Terebratella dorsata (Gmelin). 
The fossil species, which comes from the Glauconitic Bank formation (Pleistocene) 
at Cockburn Island, off Graham Land, West Antarctic, is described and figured by 
Buckman (1910, p. 18, pl. i. figs. 17-17d), with the remark that Terebratella 
