J. W. Jackson—Brachiopod Morphology. 23 
in defining genera, but their presence or absence is also an important 
character separating the two sub-families Magellaninee and Dallinine. 
' They appear to be entirely absent from the Magellanine, but are 
always present in the true Dallinine, even in fossil ; genera referred to 
this group. 
The generic position of Zerebratula spitzbergensis, Dav.,is not easy 
to define. It possesses very definite dental plates which are more 
vertical than those in MMacandrevia. he cardinalia, however, is 
not unlike that of Dallina septigera and floridana, i.e. typically 
Magellaniform. 
With regard to Zerebratula frontalis, Midd., this possesses somewhat 
obscure dental plates much as in Zerebratalia. Its loop development 
and cardinalia suggest relationship with the Terebrataliform stage 
of Macandrevia cranium as figured by Beecher.’ 
Regarding the Cincta-like forms referred to Laqueus, the following 
notes, based on four of the species, may be of some interest :— 
These species fall into two groups according to the character of the 
cardinalia. Lagueus pictus (Chem.) and LZ. rubellus (Sow.) possess 
obscure dental plates curving back to the apex of the valve. The 
hinge-plates in both are almost similar, consisting of two divergent 
buttresses rising from the floor of the valve and forming the dental 
sockets and crural bases. In Z. pictus these buttresses are divided 
clear to the apex, where a small bilobed cardinal process is present. 
In ZL. rubellus there is no cardinal process, the divaricator muscles 
being attached directly to the apical parts of the buttresses. Each 
species possesses a slight mesial septum which in old specimens is 
superimposed on a broad and massive base with deep muscle imprints 
on each side. 
L. californicus (Koch) and B. blanfordi (Dunker) have better 
defined dental plates, which are almost vertical in the latter. The 
dorsal valves of both possess Magellaniform hinge-plates (as in 
Mf. flavescens); there is no cardinal process. L. blanfordi is the 
nearest to Cineta in outward appearance, as the interior margin 
is strongly indented. None of my specimens of ZL. californicus show 
the ventral plication as given by Davidson,? but only a tendency 
towards a truncated front. Possibly Davidson’s figure is incorrectly 
drawn. 
The relationship of this Cincta-like group to the remainder of the 
Dallinine is difficult to decide. The peculiar double attachment of 
the loop suggests a complete divergence from the general line of 
Macandrevian development. <ingena (type, K. lima, Defr.), a species 
also possessing dental plates, seems to be a possible Cretaceous 
representative of the Laqueus structure. 
As to the Magellanine having representativ es in northern oceans, 
this sub-family has a northern representative in Mihlfeldtia truncata 
(L.), an abundant species in the Mediterranean, and off the north of 
Spain, coast of France, etc. 
Both the Anomia truncata, Linné, and the Anomia sanguinea, Chem., 
1 ** Revision,’’ ete., pl. i, fig. G1. 
2 Op. cit., pl. xviii, fig. 6b. 
