406 J. Hall on Cryptonella, Centronella, Meristella, 
below the beak of the ventral valve not so great, nor the del- 
tidial plates so conspicuous as in species of that genus. Ona 
critical examination of the interior, 23. 
have, so far as I know, for the first 
time the positive determination of es g 
genus in our Devonian rocks. Figures 23 and 234, 2, Tlustrations 
position and proportions of the boise of Lerebratula Romingeri Win- 
are shown in fig. 23, which is an out- ell. 
line of the shell from the dorsal side, twice enlarged. eb 230 
pared so as to show in a very Ledinbaatciey manner the loop in its 
entire extent. The specimens correspond with those I have 
received from M. de Verneuil under the same name, and therefore 
we must regard them as authentic. The external form of 
ica is not unlike some of the less gibbous of Cryptonell, 
25. 
directed down 
Fig. 24. Dorsal side of 7. melonica, bagi the crural processes dire a. 
wards.—Fig. 25. Ventral side of specimen, looking into the dorsal ae : 
26. Profile view of same, the figures ‘vice! enlarged. 
and is much less gibbous than the usual forms of Waldheim 
The lamells are nearly parallel and near together, and the fa? 
is extended four-fifths the entire length of the shell, when see : 
recurved, and, turning back, extends two-thirds of the dista : 
to the _: of the “ge valve; and the crural apg es 
farther from the base of the loo oop t than is represente ed 1 ef of a 
ae Siitée of Waldheimia, and are opposite the extremly © 
Aerie loop. ie tie 
The above ae illustrate all that has been Wee 
cies, 
(To be continued.) 
