STRUCTURE OF BRACHIOPODS. 



191 



"but with no ganglionic enlargements, except in Distinct, 

 where they terminate each by a ganglion in the last two 

 posterior muscles. Morse has discovered the presence of 

 auditory capsules in Lingula. 



Eespiration is mainly carried on in the mantle (pallial 

 membrane). In Lingula the pallial membrane is divided 



into oblique transverse sinuses, which 

 run parallel to each other. From 

 these arise, says Morse, numerous 

 flattened ampullae, which are highly 



Pig. i3o.-Ampni- or wood contractile. The blood courses in 

 sinn-es. showing course taken regular order up and down these 



by the blood. After Morse. . 



sinuses, entering each of the ampullae 



in turn. Fig. 130 represents a row of five ampullae with in- 

 dications of the course taken by the blood-disks. These 

 ampullfe have not been found in Distinct, though the pallial 

 sinuses are very prominent. The breathing process is also 

 carried on in the tentacles or cirri. 



Intimately connected with the vascular system is a gland- 

 ular portion of the tubular part of the segmental organs ol 

 the Brachiopoda, which is 

 supposed to represent simi- 

 lar parts in worms as well 

 as the glandular, excretory 

 portion of the organ of 

 Bojanus in mollusks, and is 

 supposed to be depuratory 

 or renal in function. 



The reproductive system 

 of Brachiopoda consists of 

 ovaries, oviducts or 

 mental organs, Fig. 

 tind spermaries. 

 are probably separate in all Brachiopoda (Morse). 



The ovaries are attached in Discina and Lingula to the 

 delicate vascular membranes of the large sinuses in the pal- 

 lial membranes, the vascular membranes being thrown into 

 conspicuous ruffs when the eggs are ripe. In Terebratulina 

 and Rhynchonella they are not only similarly situated, but 



seg- 



-iqi Fig. 131. Segmental organs of Brachio- 



& J-dJ-j pods, a, Discina ; b, Terebratuliua. After 



The sexes Morse - 



