144 DE. T. DAVIDSON ON EECENT BRACHIOPODA. 



which did not appear to differ from those of Waldheimia as described by Hancock, 

 as far as I was able to discover. The great brachial canal was rendered conspicuous by 

 a band of cartilaginous substance which seemed to form its external covering, or rather 

 beneath which it was situated, and Avhich was longitudinally striated. The external 

 edge of the membranes, between which the apophyses were formed, was directly attached 

 to the pallial lobes at the points where the apophyses are attached to the muscular disks 

 of attacliment already described. On either side of this attachment, however, was a 

 kind of pocket, opening externally, where the brachial and pallial membranes did not 

 coalesce ; and, there being one on each side of the point of union, there were conse- 

 quently four in all, two on each side of the septum. Tiie drumhead membrane, covering 

 the space inside of the brachia, was translucent white or opalescent, and quite thick and 

 tough towards the middle of each lobe." 



[i. c. p. 23.] " I am inclined to think that an eri'or has been perpetuated in regard to 

 the position of the mouth of Megathyris decollata. It has been figured and described by 

 Woodward as being of a circular form, and situated in the midst of the drumhead membrane. 

 It is certainly not so situated in Cintella ; and I do not believe that it is in Megathyris, 

 though I have only seen dry specimens. In the present species it is placed, as in all the 

 TerehratuUdcs, at the back of this nieml)rane, just in front of the posterior junction of the 

 brachia, and at the bottom of a deep transverse groove which is of a stout membranous con. 

 sistency, and the two sides of which, for convenience' sake, I have called the lips {labia). In 

 the present species the oral groove is situated far back and close to the brachia, which are 

 exceptionally long behind it, as already described. It is, in fact, entirely hidden by them 

 until they are laid back. The groove is very long and quite deej), the entrance to the 

 oesophagus being trumpet-shaped and flattened transversely. Were the brachia disposed 

 as in Woodward's figure, the oral groove would be hidden. I am disposed to think that 

 this was really the case in the specimen figured, and that the extraordinary circular 

 motith there figured was an accidental lesion of the dry tissues, which might easily be 

 taken for a mouth of so small an animal. The labia, in all the Brachiopods I have 

 examined so far, have invariably exhibited a tinge of darker colour than the surrounding 

 tissues. The present case forms no exception. The posterior lip presents a small promi- 

 nence in the median line, and the anterior lip a small emargination or concavity below 

 this prominence. This structure is also common to all the Brachiopods I have examined. 



"The oesophagus is wide, transversely flattened, with thin walls, and of an orange 

 color. It enters the stomach nearly at a right angle, without much dilation. The 

 stomach is oval with thicker and firmer walls ; the inner lining appearing slightly villous 

 and rugose. The intestine is not diiferentiated from the stomach on the lower side, but 

 on the upper side a deep groove occurs at the juncture. The canal is stout and thick at 

 its lower extremity, tapers slightly, and terminates in a somewhat bulbous, Init pointed 

 csccal extremity, attached to the perivisceral membrane. The various membranous bands 

 which support the alimentary system present no differences from the homologous struc- 

 tures in other species of TerehratuUdce. The stomach was filled in each case with a 

 yellowish flocculent matter. The hepatic lobules resembled those of other species, entering 



