FROM NORTHWESTERN EUROPE 81 
long, stout, subparallel dental lamellae. The hinge apparatus is strongly developed 
with massive crenulated teeth and strong lateral denticulae. 
Brachial valve. The most obvious feature is the presence of a median septum 
and well developed septalial plates forming a septalium. The crural bases do not 
become apparent, as seen in transverse section, until after the hinge plates have 
divided and the septalial plates disappeared. The crura are radulifer. The sockets 
are crenulated and both the inner and outer socket ridges are strongly developed. 
DISTRIBUTION. The species has only been recorded from the Helmsdale area of 
Sutherland, Scotland. 
OccuURRENCE. The only known occurrence is in the Kimmeridgian ‘“ Boulder 
Beds ’’ of the Helmsdale area, east Sutherland, Scotland. Bailey and Weir (1935) 
suggested that the rhynchonellids, together with the terebratulids and corals, owed 
their presence in these beds to the effects of submarine faulting. They suggested a 
near-shore fault scarp which, “‘ separated a comparatively shallow-water facies, 
characterized by rounded pebbles, sand, Rhynchonella, Terebratula, Ostrea, sea 
urchins corals, etc. from a comparatively deepwater facies, characterized by mud, 
debris of land plants, ammonites etc.’’. The rhynchonellids etc. were then swept 
over the scarp edge by the movements of the fault and the accompanying 
tsunamis. 
Ager (19654), accepting this hypothesis, suggested that the S. sutherlandi 
inhabited, “‘ sublittoral, non-depositional sea floors’; the rarity of the species then 
being accounted for by the infrequency with which such deposits are preserved. 
However, although no other representative of the genus occurs in Britain, S. moeschi 
(Haas) is present in the “ Rauracian’”’ of the French and Swiss Jura. Material of 
the latter species has been given to the author by Dr. Enay of the University of Lyon 
and he has stated (personal communication, 1965), that S. moeschi, at least within the 
Jura meridionale, always occurs in association with corals. From this it would also 
seem possible that S. swtherlandi inhabited shallow marine environments and was 
not necessarily restricted to rocky shores. The presence of corals at Helmsdale 
indicates the possibility of a reef environment being available. 
REMARKS. It appears that S. sutherland: has not been further described since 
Davidson in 1878 and during this time there have been only two tentative generic 
assignations. In the first, Buckman (1918), placed it in his genus Rhactorhynchia 
but although he indicated his uncertainty he did not discuss the matter. Ager 
(1965a), suggested the possibility of swtherlandi being in the genus Russirhynchia 
Buckman, which is otherwise restricted to the Russian Platform. The present 
author, however, prefers to attribute the species to the genus Somalirhynchia Weir. 
Reproduced below, text-figure 28, are the serial sections given by Muir-Wood (1935) 
for the type species, S. africana Weir, and it can be seen that they show a striking 
resemblance to those of S. sutherlandi. Externally the species are also comparable 
in general shape, ribbing, and form of the beak and the pedicle opening. Both 
internally and externally “‘ R.”’ sutherlandi appears to be much closer to S. africana 
than to the type species of Russirhynchia namely, R. fischeri (Rouillier). 
