538 
this is in a general way very similar to that of Exdolobus avonense 
during the ana- and metanepionic substage, but in the paranepionic 
a dorsal furrow appears which is not present in Endolobus at the 
same early age. ‘The longitudinal ridges appear also in this sub- 
stage, the previous substages being smooth. ‘The umbilical perfo- 
ration, Fig. 15, shows the very abrupt bend which takes place at 
the,end of the metanepionic substage just before the dorsal furrow 
appears. ‘This furrow is broad and well defined and cannot be 
said to be correlative with a nephritic outline. The section of the 
whorl at this age, Fig. 17, still retains in some measure the tri- 
gonal outline of the ana- and metanepionic substages. It has be- 
come temnocheilan or trapezoidal through the great broadening of 
the abdomen, but if no furrow were present it would have to be 
described as a modified subtrigonal (see Fig. 17 which gives the 
form correctly). It is in no sense nephritic, although obviously 
_ transitional and standing between the preceding digonal and suc- 
ceeding nephritic outline shown in the ananeanic substage. This 
substage occupies the last quarter of the first whorl. The broaden- 
ing out of the furrow, which also increases in depth, although the 
curvature remains constant, can be observed in this same substage 
while the volution is still free, also the advent of a purely nephritic 
outline and a minute annular lobe in the middle of the dorsal lobe. 
The siphuncle shifts somewhat nearer the centre. 
Contact takes place on the ventral side of the ananepionic volu- 
tion, but the apical end is not free. The dorsal sutures in conse- 
quence of the annular lobe have a much spread-out or flattened V 
shape like those of Lxdolobus avonensis at a later stage and in the 
contact furrow (see Fig. 37, Pl. viii). 
The form of the adult also resembles that species. The sutures 
have ventral saddles, lateral lobes and dorsal lobes in the ephebic 
stage and the outline is nephritic. The annular lobe does not in- 
crease much in size with advancing age and seems to disappear in 
this stage. Although the locality of this specimen is unknown, the 
probable age is Devonian. 
Fearing to trust my own conclusions in this instance, and having 
one valve of a Brachiopod which was detached from the specimen 
described above, I sent the latter to Mr. Charles Schuchert in the 
National Museum, Washington, for determination. This gentle- 
man very kindly gave me the benefit of his great special knowledge 
of this group and returned it to me with some other specimens of a 
