BRACHIOPODA. 841 
septum. Their anterior portion is always free while their pos- 
terior portions are sometimes coalesced into a single piece. In 
the brachial valve there are two short crural plates not rising to 
more than one-third the height of the shell; these may remain 
independent or sometimes unite to form a single piece. 
The muscles are attached between and on the convergent 
plates, and, in the brachial valve, also in front of them. 
Surface-sculpture variously punctate. Shell-structure appa- 
rently fibrous. 
Type, Porambonites intermedia, Pander. 
Distribution. Silurian. 
Noetlingia, Hall. 1893. 
Shells exteriorly like Poramsonirzs, with long, straight hinge- 
line, well-developed cardinal areas and biforate 
beaks. 
There is a spondylium in each valve, that of 
the pedicle-valve being, at the outset, the larger, 
and continuing further forward than the other. 
Both are supported by a stout median septal fit eae peak 
callosity, which, in the brachial valve, widens ™e» of Noetlingia 
4 C Tscheffkini, DE VER- 
and becomes lost in the thickened shell-substance xxur cep). 
of the muscular region; that of the pedicle-valve becomes 
narrowed anteriorly, and eventually leaves the spondylium free, 
SS Bl EES es 
Fie. 444. Fie. 445. Fie. 446. 22074 | LF 1e.{447.° 
Fic. 448. Fie. 449. Fie. 450. 
Fias. 446-452.— Transverse serial sections of a single specimen of Noetlingia Tscheffkini, 
showing the structure of the internal apophyses and septa. In all the sections the pedicle- 
valve (P) is above, the brachial valve (8) below. 
or nearly so. There is a simple linear cardinal process in the 
spondylium of the brachial valve. 
Type, Woetlingia Tscheffkini, De Verneuil (sp.). 
Distribution. Lower Silurian. 
106 93 
