LIVING BRACHlOPODA. 339 



Mesenteries and Perivisceral Bands. 



The various bands and mesenteries so characteristic of the Vermes are marked 

 features of the Brachiopoda. These bands not only hold in place the various internal 

 organs, but from them spring, as in many worms, the genital products. A transverse 

 section of Glottidia, just back of the stomach, reveals a dorsal and a ventral mesentery' 

 and lateral bands springing from the intestine and attached to the various parietes. A 

 dorsal view of the intestine of Glottidia (50: 8) shows the line of attachment of the 

 dorsal mesentery running back for a short distance from the abrupt collar, which forms 

 the posterior edge of the stomach, and then dividing to the right and left. The right 

 line of attachment runs abruptly down the side of the intestine reaching the middle of 

 the ventral surface (50 : 7) , and then back again and obliquely across the dorsal surface 

 and on posteriorly. The left branch of attachment apparently continues along the left 

 side of the intestine. These lines mark the attachment of the membrane known as the 

 iho-parietal band (47 : l) ■ This membrane stretches across the coelomic cavity, its edges 

 touching the oblique muscles and connecting also with the nephridia on each side 

 and just back of the nephrostomes, sending bands to the lateral coelomic walls. It follows 

 the upper inflection of the intestine and sends out a broad band to the posterior adductor 

 muscle. Another sketch is given (48 : "3) , showing the appearance of the posterior bend 

 of the intestine with a band running to the posterior adductor. A transverse section of 

 the mid-gut presents the appearance of the ilio-parietal band, upon which may be seen 

 delicate branches which are apparently vascular. The coelomic cavity seems to be 

 ensheathed in a peritoneum which is attached to the dorsal parietes and seems to rest on 

 the oesophagus and stomach and runs down on the right and left to the ventral region. 

 A comparison with the oesophageal mesentery of Phoronis would be of interest in this 

 connection. This membrane is quite vascular, and an injection from the peduncular 

 cavity filled these vascular ramifications without entering the pallial sinuses or the 

 coelomic cavity (54 : 1, 2) . Further remarks will be made on this matter under Cir- 

 culation. 



The gastro-parietal band in L. lepidula forms an almost complete wall between what 

 might be called the gastric cavity and the perivisceral cavity. Its dorsal boundary is 

 very conspicuous through the translucent shell and appears tendinous. On each side 

 where this band joins the lateral coelomic walls, muscular fibres are seen. Blochmann 

 observed these muscles in L. anatina and has called them gastro-parietal muscles (48 : 6) . 

 In D. lamellosa, just back of the stomach and partially obscured by the stomachal glands, 

 a band is attached on each side, which runs across the coelomic cavity to the right and 



