DK. T. DAYIDSOX OX EECENT BRACHIOPODA. 137 



branched canals The minute structure of the internal skcletou is like that of the 



inner layer of the shell, there are no canals present The mantle which lines the 



internal surface of each shell is formed hy two evaginations of the body-wall On 



the outer surface the mantle is in direct communication with the organic basis of the 

 shell. No setse occur in the mantle of Argiope. Into each of the canals which pierce 

 the shell, the mantle sends a diverticulum. This is a hollow tube which fits exactly into 

 the calcareous canal, but, unlike that, is closed at its outer end." ]\Ir. Shipley then 

 describes at some length the papilte and their supposed functions; but space will not 

 aUow us to transcribe his account of them, my object being merely to give a few extracts 

 from his valual)le paper, which should l)e read in its entirety. 



"The lophophore [p. 499] lies entirely in the dorsal shell, it forms a great part of the 

 body wall of the animal. The shape is an oval, the border running parallel with the margin 

 of the shell, except at the anterior median portion Mliere there is a narrow deep indentation 

 dividing the lophophore nearly into two equal halves ; this is caused by the triangular 

 septum mentioned above. These halves correspoiul with the two arms of other Brachio- 

 pods. The lophophore [p. 500] is attached anteriorly and anterio-laterally to the mantle 

 lining the shell, postero-laterally it is attached to the free edge of the triangular plates ; in 

 the median postcn-ior portion it is continuous with the remaining body wall. In the median 

 line it is attached on each side to the free edge of the septum. The lophophore carries 

 round its margin a number of tentacles ; the number increases with the age, but is usually 

 from 70 to 100. "Within the bases of the tentacles a lip runs entirely round the lopho- 

 phore, forming a groove ; the mouth lies in the posterior median portion of this groove. 

 The remainder of the lophophore is composed of a membrane which covers some of the 

 viscera ; the centre of each half of this membrane is rather thickened and presents in 

 the fresh state an ill defined whitish patch. The tentacles usually lie ])ointing towards 

 the centre of each half, but they are often curved and sometimes coiled like a cork- 

 screw Around the edge of the lophophore, between the base of the tentacles and the 



origin of the lip, there runs a canal in the substance of the lophophore . . . Thus the cavity 

 in the lophophore communicates with part of the body cavity. . . . The protrusion of the 

 tentacles [p. 501] is probably brought about by forcing in a perivisceral fluid, but their 

 retraction and coiling movements are probably occasioned by tlie muscular fibres which 

 lie in their interior. 



" The mouth [p. 502] is a transverse slit in the median posterior part of the ciliated 

 groove ; it leads into a somewhat narrow oesophagus which lies against the posterior 

 curved border of the triangular septum. At the bottom of this border, the oesophagus 

 turns towards the posterior end of the animal and immediately enlarges into the stomach. 

 This is globular in shape and receives upon each side the opening of the liver. The 

 stomach narrows posteriorly and passes into a conical intestine which bends towards 

 the ventral shell between the two brood pouches, and ends between the occlusor muscles. 

 There is no anus. 



" The liver [p. 503] consists of two branched glands lying one on each side of the 



alimentary canal The blood is contained in a number of vessels which run iri'egu- 



larly in the tissues of the body, but which chiefly lie in the mantle and that part of the 

 body wall lining the shell." 



