Morse. ] 368 [March 19, 
The Tunicates, Amphioxus, and many important groups, which 
have taught us so much regarding the affinities of classes supposed 
to be widely separated, had no hard parts to preserve, and nothing 
by which we could make out their structure. Even the worms, with 
the exception of the Cheetopods, have left us nothing, and the last 
named group are known to us only by their tracks, spines, and tubes 
left in the rocks. Even the hard leathery peduncle of the fixed 
Brachiopods has, in one or two instances only, been preserved.! 
The earliest forms of Brachiopods thus far met with, are those 
with thin, diapnanous shells (as in the Lower Lingula Flags), and 
even before these forms existed we can legitimately conceive the 
primary existence of certain Brachiopods, with the peduncle endowed 
with high functional importance, and the anus terminating posteriorly, 
as in those Annelids, like Lysilla, where the caudal portion is apo- 
dous, scarcely annulated, and devoid of setae. Later appeared Brach- 
iopods with an anterior termination of the intestine, as in Pho- 
ronis and certain sipunculoid worms, and finally the peduncle became 
attached, and the anus obliterated. 
In regarding the relations of the Brachiopoda, let us suppose that nothing 
was known of such a form as Lingula, and that the only forms of which we 
had any knowledge, were the short and wide forms, like Chonetes. It would 
certainly be considered a wild supposition to suggest the possible existence of a 
Brachiopod, in which the shell should be translucent and elastic, four times as 
long as wide. A peduncle partially annulated, nine times as long as the body, 
capable of sharp vermian contortions, having a rapid circulation within, in- 
cased in a sand tube, with the animal living free in the sand, and having a 
limited power of locomotion. Surely it would tax the powers of the imagina- 
tion more to concéive this form than to simply endow a sedentary Annelid, like 
Protula, with the cephalic collar extending beyond the arms instead of sur- 
rounding the base, and secreting a dorsal and ventral plate, with the anus 
terminating at the side instead of behind. 
The presence of prominent dorsal and ventral plates enclosing the arms from 
which the arms in some cases are protruded and the consequent developement 
of special muscles to move these plates, form the only marked differences be- 
tween the Brachiopods and the Worms. In the Gephyreans as in the common 
Sipunculus, for example, where the anterior portion is highly contratile, pon- 
derous retractor muscles are developed with widely expanded bases, as in the 
Polyzoa and in many Brachiopods. 
1In the Museum of the Geological Survey of Canada is aspecimen of Hichwaldia. 
subtrigonalis Billings, from the Black River Limestone, Lower Sil., showing the 
silicified peduncle nearly as long as the shell, photographs of which Mr. Billings 
sent me. ; 
ee OR POR OS SNC ORE PERT 
So 
