60 DR. T. DAVIDSON ON RECENT BRACHIOPODA. 



forward from the under lip of the mouth and foUowing the downward curve of the 

 median lohes. In this great extension of this membrane this species differs from T. caput- 

 serpentis and W. australis, in which species the cirrhi of the median lobes touch at their 

 extremities, and are separated by only a very narrow sti"ip of membrane between their 

 bases, so that the appearance is almost as if there was but a single broad band of cirrhi 

 in the median line. This intervening membrane in ordinary specimens of W. fioridana 

 is about "24 of an inch in width at its narrowest visible portion. The upper and lower 

 bands of cirrhi in the lateral loops are also much more widely separated by a similar 



membrane than in W. australis The spiral portion in the middle lobe makes 



about two complete turns The mouth is, as usual, just in front of the posterior 



junction of the brachial bands, and is in a rather long flexuous groove, tlie edges of 



which are of a dark brown colour, and somewhat thickened The oesophagus is 



about half as long as the intestine, and has a slight curve, of which the convexity is 

 anterior ; it is transversely flattened close to tlie mouth, and is a little compressed 

 laterally, behind that portion. It is of a nearly uniform calibre throughout. It has 

 quite a thin lining membrane, which becomes thicker, though still smooth, in the 

 stomach, and quite thick and longitudinally plaited in the intestine. The stomach is 

 well differentiated from the alimentary canal and intestine, and is of an oval shape. It 

 is embraced by the hepatic digitations, which are of a greenish-yellow color, and empty 

 into the stomach by four ducts. The orifices of these ducts are of a compressed oval 

 shape, obliquely inclined, and the anterior pair, which correspond to the right and left 

 anterior congeries of hepatic digitations, are twice as large as the posterior pair, which 



similarly correspond to the anterior lobes or bunches of digitations The intestine 



is twice as long as the oesophagus, of uniform calibre, and perfectly straight. It leaves 

 the stomach abruptly without any dilatation of the portion adjacent to the latter 

 organ, and reaches aljout half-way to the dorsal valve. The heart is situated behind the 

 junction of the stomach and intestine. The termination of the intestine is abruptly 

 rounded off and not at all pointed. It is entirely closed, and is upheld by the mesentery. 

 It is also of a much darker color than the rest of tlie alimentary canal, being of a 

 deep chestnut brown hue." 



" The great pallial sinuses and their ramifications in W. florkkma are of much less 

 extent and disposed in quite a different manner from that which obtains in W. 

 australis. The hfemal pallial system consists essentially of four branches which are 

 remarkable for their straight course and the paucity of their ramiticatious. The neural 

 pallial system is very similar, wdth a greater number of small sinuses about the peri- 

 visceral cavity, but in both lobes the narrowness and small extent of the sinuses, as 

 compared with those of other species, is very marked, and the same is true with regard 

 to the ovaries. But a very few exceedingly delicate spicukTe were observed in the floor 

 of the greater sinuses. The lieart consists of a very minute pyriform vesicle situated 

 behind the intestine at its junction with the stomach, and sending one vessel in the 

 hsemal direction along the median line of the stomach, and another on each side laterally. 



The ovaries are very limited in extent and principally confined to that portion 



of the sinuses which surrounds the visceral cavity, only their ultimate extremities entering 



