the signitication of this object; it can scarcely he a nervous ganglion; as it does not lie in 

 the substance of the body itself, but only in the thin external skin which encloses the body. 

 The stomach and the intestine usually shew in the living animal a bright opaque yellowish 

 brown color, which color seems mainly to be derived fi'om the contents. When the stomach 

 and intestine are more empty, they shew a far paler yellowish white color. The walls of both 

 shew plainly a fine cellular stmcture. 



It is evident that the digestive system in the Rhabdopleura differs, in many points 

 which have not been remarked by Allman, from the normal system of the Polyzoa. In the 

 latter the stomach usually consists, as is well known, of 2 distinctly separate parts, one shorter 

 cylindrical cardiac part, and a longer and wider pyloric part, which ends in a large rounded 

 bottle-shaped Ca;cum (cul de sac). Therefore the intestine usually takes its origin, in these, 

 high up, or about on a level with the transition of the cardiac part to the pyloric part; while 

 in the Rhabdopleura, where no such division of the stomach occurs, the intestine proceeds 

 from the jiosterior end of the stomach or fundus, as the immediate continuation of the same. 



The Tentacular Arms. 



The tentacular Corona, or Lophophore, situated in the Rhabdopleura on the anterior 

 end of the body, is of a totally different appearance from that of the other marine Polyzoa, 

 while on the other hand it appears at first sight to shew an unmistakable resemblance to 

 that of most fresh-water Polyzoa (P. hippocrepia) and is also thus represented by Allman. 

 However when it is more closely examined, it displays many essential differences; although 

 by its strongly marked bilateral symmetry, it appears to be most nearly connected with the 

 same, in respect of the semilunar or horse-shoe form peculiar to them. 



As in the said fresh-water Polyzoa, the Idphophore or tentacular frame does not form 

 a circular ring, but is drawn out into 2 lobes or arms, each of which bears a double row of 

 tentacles. These lobes or arms (fig. 3. 4. 5. &c. d.) which also here proceed from the dorsal 

 side, are however considerably longer and narrower, or more cylindrical than in any other of 

 the known Polyzoa; and while in those freshwater Polyzoa they only form a part of the ten- 

 tacular corona, they represent here the whole lophophore, as it is only on these arms that 

 the tentacles have their place. The tentacles in the Rhabdopleura do not form, as in the 

 other Polyzoa, a continuous series, but are interrupted, as well dorsally as ventrally, by an 

 evident interval; in other words, nr have not one single feutaciilar croioi, hut 2 symmetrical 

 tcntandar arms, which take their beginning on each side of the anterior part of the body, and 

 extend out from the same dorsally and diverging to each side. If we examine these tenta- 

 cular arms in the living animal we tind that they are also in many respects different from 

 the lophophore of the Hippocrepia. While the latter always retain unchanged their form 

 and somewhat inclined direction, the tentacular arms in the Rhabdopleura are in a high degree 

 flexible and variable in their direction relatively to the body of the polypide and to each 

 other. As long as the polypide is withdrawn into the cell, they are always (see rig. 14), 



