HUXLEY, ON APPENDICULARIA FLABELLUM. 187 



scribed by Gegenbaur (c), at once strike the eye, not only from 

 their size, but from the vehement action of the king cilia with 

 which they are provided. I can in no way account for having 

 overlooked them, and I see nothing for it but to accept the 

 fact of the omission as a practical lesson in scientific charity. 

 The pharynx passes on each side into a funnel-like prolonga- 

 tion (Z», c), with its apex directed towards one side of the rectum. 

 The dilated base of this prolongation is continuous with the pha- 

 rynx, its comparatively narrow apex opens externally beside the 

 rectum. In the mid-length of this conical canal is a thick- 

 ened circular band (fZ), formed towards the pharynx of a series 

 of cella?form bodies, placed in a single series, end to end, and 

 externally to this of a transversely-banded substance. It is 

 Iroin this latter portion that the cilia take their origin. They 

 are arranged in several tiers, are very long, and have a strong 

 wavy motion. 



That we have here a direct communication between the 

 pharynx and the exterior, and not, as Gegenbaur states, a 

 communication between the pharynx and certain internal 

 canals, was made clear to me, not only by direct observation 

 of the external apertures, but by feeding the animals with 

 indigo. In two specimens this experiment succeeded per- 

 fectly ; but it was very curious, that while in the one the 

 current set in at the mouth and out at the apertures, in the 

 oiher the current was in precisely the opposite direction, in 

 at the apertures and orit at the mouth. The wide stomach is 

 bent backwards upon itself, so that its two halves or lobes are 

 pretty nearly parallel, leaving, however, an interval in which 

 the heart is situated. The right lobe is quadrate in outline, 

 and undivided, but the left is irregular and lobulated. The 

 inner surface of the stomach is papillose and ciliated, and 

 many yellowish granules are scattered through the substance 

 of its wails. The intestine arises from the upper angle of its 

 left lobe, bends to the right, and then, when it reaches the 

 middle line, passes forward to the anal aperture. The i-ectum 

 is ciliated, and, as before, I was unable to find any trace of 

 the tubular " hepatic" system, so general among the other 

 Ascidians. 



The heart (t>) is large, and occupies a transverse position be- 

 tween the two lobes of the stomach, laterally, being more 

 closely in contact with the right lobe, and the testis and base 

 of the caudal appendage, antero-posteriorly. I was unable to 

 observe any blood corpuscles, nor could I discover any sign 

 of that reversal of the direction of the contractions so general 

 among the other Ascidians. The absence of corpuscles would 

 have rendered it almost impossible, under ordinary circum- 



