500 Dr. J. Allan Thomson—On the Terebratellide. 
however, it is desirable that a further study of the young stages of 
Mihifeldtia should be made. Had Deslongchamps presented side 
views of the specimens he figured, all ambiguity would have been 
avoided. 
In its further development J. truncata diverges greatly from the 
Terebratelliform ontogenetic series. Apparently what in the adult 
loop resembles the jugal band of a Zerebratella is really the original 
bottom part of the primitive ring, little modified except in size. 
The anterior extensions of the ring become greatly enlarged, and with 
them the primary lamelle increase in length, although remaining 
attached to the lower sides of the ring at their point of origin. 
Neither Davidson, Deslongchamps (1884), nor Fischer & Oehlert 
(1891) show in their figures any sign of lacune such as occur in 
Frenulina, but in a specimen from the Mediterranean in the Dominion 
Museum, Wellington, they exist as narrow slits separating for some 
distance the anterior extensions of the primary lamelle from the 
anterior extensions of the ring. 
There is another genus which by an anterior extension of the 
secondary part of the loop prevents some resemblance to Dihlfeldtia, 
viz. Campages, Hedley (1905), which occurs on the south and east 
coast of Australia. In the type species, C. furcifera, Hedley, there 
is also a slight development of lateral lacune, but these do not appear 
to bepresent in the only other known species, C. yaffaensis (Blochmann).* 
Through the kindness of Dr. J. C. Verco, of Adelaide, I have been 
able to examine a small series of the young of the latter species. 
In these the typical high septum of the Magadiniform and pre- 
Magadiniform stages of Zerebratella is seen, and up to the Magadini- 
form stage there is no marked difference from the young of Terebratella 
except that the ribbon of the ring is broader and extends further 
forward. The later stages are not well displayed by the series, but 
it is evident, from the occurrence of a Magadiniform stage with 
widely separate attachment of the primary lamelle and of the ring 
on a high septum, that Campages is not a close ally of Mihifeldtia 
but an undoubted member of the Magellanine, with a loop representing 
a specialized development of the Magelliform stage. 
There are two other species that should be considered in this 
connexion, viz. Megerlia Willemoest, Davidson, and TZerebratella fur- 
culifera, Tate. The former is a recent species obtained by the 
Challenger Expedition off T'wofold Bay, New South Wales, and has 
a loop resembling that of an early Terebratelliform stage of Zere- 
bratella, except that the reflected part of the loop is attached to the 
septum by two descending lamelle, thus enclosing a triangular space. 
In 7. furculifera, Tate, an Australian Tertiary fossil, the same kind 
of connexion with the septum occurs, but the brachidium appears to 
be rather more advanced, and comparable to a late Terebratelliform 
stage. These two species occur in the same region and are thus 
probably related. Their loop characters are quite distinct from those 
1 Originally described by Blochmann (1910) as Magasella jaffaensis and 
ascribed to Campages by Hedley in 1911. Hedley also considered Magellamia 
Joubini, Blochmann, a species of Campages, but this species appears to be 
correctly placed under Magellania. 
