FROM NORTHWESTERN EUROPE 9 
series of strongly asymmetrical species, as typified by 7. inconstans (J. Sowerby) 
from the Kimmeridge Clay. The reason for this somewhat bizarre development is 
not understood ; however, it is interesting to note that the individuals concerned 
can be inverted and still retain the same form of anterior commissure. This is 
particularly obvious in the more globose specimens of T. tmconstans in which the 
brachial valve was inflated to such an extent that the pedicle must have atrophied. 
Given the subspherical appearance of these inflated specimens, their lack of a pedicle 
and the fact that they apparently lived in a high energy, perireefal environment, it 
seems reasonable to assume that the development of asymmetry was related to these 
facts. That Torquirhynchia species can be inverted and still retain the same form of 
anterior commissure may possibly have been of advantage in that, as the right and 
left halves of the mantle cavity are physiologically independent (Orton, 1914), at 
least half of the lophophore system would have a water intake well clear of the 
bottom. 
With the exception of 7. cf. T. astieriformis, which was collected from around a 
small sponge reef, the genus has always been found associated either with corals or 
with “reef” limestones. Torquirhynchia seems to be completely absent from the 
sponge reef facies of the Swabian and Franconian Alb ; T. speciosa is found in the 
Kelheim area but the “‘ Diceras Kalk ”’ in which it occurs has much closer affinities 
with the fauna of the Stramberk Limestone of Czechoslovakia. 
Apart from Torquirhynchia, the only other genus to have colonised the areas 
around coral reefs is Somalirhynchia Weir. S. moeschi (Haas), which occurs widely 
in the central French Jura, is always associated with corals according to M. Enay 
(personal communication, 1965) and this was certainly so at the one locality where 
it was collected by the author. It is considered that the presence of corals in the 
Kimmeridgian Boulder Beds of Sutherland is significant in accounting for the 
occurrence of S. sutherlandi. This occurrence of S. sutherlandi is discussed in some 
detail under the specific description. It must be stressed that both Torquirhynchia 
and Somalirhynchia appear to be strictly perireefal. Elliot (1950) has suggested that 
the absence of brachiopods within reefs is probably a result of the coral polyps eating 
the brachiopod larvae. 
(c) Sublittoral, muddy sea floors. 
This is the remaining major environment in which rhynchonellids have been 
collected. As stated by Ager, it seems reasonable to assume that this is a deeper 
water facies than those discussed above, but this need not be so and the present 
writer would agree that the grain size of the substratum seems to be more important 
than the actual depth. With regard to this latter point, at various localities in the 
southern French Jura Lacunosella arolica occurs in a marly facies. However, as 
stated above, it is invariably associated with sponges and it is considered that these 
represented the substrate as far as the lacunosellids were concerned and consequently 
the presence of sponges is the determining factor rather than sediment or depth. 
Other genera which occur in this environment include Rhynchonella, Thurmannella, 
Echinirhynchia and Monticlarella. Of these it is suggested that forms such as T. 
