134 WALTER GARSTANG, M.A. 



aperture, which is slightly nearer the anterior than the posterior end 

 of the body. The body is attached by almost the whole of the left 

 side, which is deeply furrowed and irregularly pitted. The test is 

 overgrown by extensive colonies of the Polyzoon Cylindrcecium 

 dilatatum. 



Upon removal of the test, the extent of the dorso-ventral com- 

 pression is at once noticed. The ganglion and cloacal siphon, instead 

 of occupying their usual position upon the apparent left of the body, 

 are in the median line of the upper side ; and the whole of the 

 viscera appear to have suffered a similar rotation through 90 degrees. 

 Strictly speaking, however, the viscera present exactly the same 

 morphological relations to the rest of the body as in the normal 

 individuals described above. 



The generative organs are well developed, and the oviduct and vas 

 deferens are remarkably dilated. The former contains numerous ripe 

 ova, of small size ; and the latter is filled with a mass of spermatozoa. 



The only difference of any importance in the pharynx is the presence 

 of a pharyngo-cloacal slit* ^ inch in length, in the usual position 

 opposite the cloacal aperture. 



The prcebranchial zone is closely studded with minute papillae. 



The growth of the aperture of the dorsal tubercle has progressed 

 still further ; both horns are now curved inwards. 



Epipharyngeal groove and dorsal lamina as in younger specimens, 

 but the lamina is a little deeper ; the ribs are very strong and regular, 

 the teeth rather short, very regular, without intermediate smaller 

 ones ; the concave side of the lamina as described above. 



Behind the oesophageal aperture is a long smooth area (the " post- 

 buccal raphe " of Roule), bounded on the left by a continuation of 

 the dorsal lamina, and on the right by a series of terminal elevations 

 of the horizontal membranes of that side, as in A. mentula. 



Branchial apparatus. — This is much as in younger specimens, 

 but the arrangement of horizontal bars into primaries and secondaries, 

 <kc, is less obvious, owing to the increase of the quaternary vessels 

 which are in many parts of the pharynx completely formed. Rudi- 

 mentary quarternaries are rare. 



The papillae at the junctions are bluntly conical ; the intermediate 



* See p. 144. 



