378 ANATOMICAL CHARACTERS OF PEROPHORA HUTCHISONI. 



still further concealed by the gritty coating. The former is situated on the upper surface 

 near the free extremity, holding a suhterminal position, so that in the mutual relation- 

 ship of these openings, Fcrophora, and indeed also other pedunculate forms, may be 

 said to exhibit an approach to Boltenia. 



The surface of the mantle is beautifully marked with yellow branched and reticulated 

 lines, similar, no doubt, to those which have been noticed in Claveli/na, indicating the 

 distribution of vessels. 



The endostyle occupies a portion of the dorsal surface extending from near the 

 branchial opening to the inner extremity of the sac, where it presents a slight curvature 

 towards the oral orifice. 



The transverse bars of the respiratory network are about five in number, and join the 

 endostyle in a direction nearly parallel with a line drawn through the branchial and 

 cloacal openings, while the much smaller and more numerous longitudinal nervures lie 

 parallel with the endostyle. The beautiful network so formed is invested with a stout 

 epithelium, and its meshes are fringed with vibratUe cilia. 



The mouth is situated at the anterior and inferior part of the respiratory cavity, and 

 opens into a short cylindrical oesophagus which passes downwards and backwards to join 

 a comparatively small and subglobular stomach. The intestine arises from the dorsal 

 surface of the latter organ, and after having performed a graceful flexure by turning 

 forwards and outwards, terminates in a very ample atrium or open space between the 

 exterior of the branchial network and the muscular coat. The lining of this space is very 

 obviously continuous through the branchial sUts with that of the respii-atory chamber. 



The generative organs, as in most compound Tunicata, are included within the intes- 

 tinal loop, and, on account of the close proximity of the cloaca, the ducts are necessarily 

 very short. 



Two distinct canals, alternately interchanging the office of artery and vein, are circum- 

 stantially described as occupying the pedicels of the British species of Ferophora, but I 

 cannot say that I have found such to be the case in the Australian one. There is, how- 

 ever, much difficulty in determining the question, on account of the obstacles which the 

 superficial gritty particles and the pigmentary matter of the mantle and tubules oppose 

 to the observation of the vital phenomena of the animals. I think I may safely affirm 

 that no such arrangement is traceable in Didemniimi, Botryllus, and numerous other 

 Tunicata, both simple and compound, that might be adduced ; and if it be actually present 

 in the British Ferophora, I cannot help regarding the fact as something quite exceptional 

 in the group. 



May 1858. 



