REPORT ON THE PENNATULIDA. 



25 



The only specimen of this UmheUuIa Ijrought home by the Challeugor is in a very 

 bad state of preservation ; nevertheless it is of great interest, as it is the only known 

 Uvibellula which resembles the Umbellula of Ellis and Mylius so much that it seems to 

 be the same species, or at least to come very near it. The lower enlargement of the 

 stalk is cylindrical below, and ends in a small bulb, in which the pointed end of the axis 

 is contained. The upper portion of the lower swelling is quadrangular, of the same form 

 as the axis, and larger than the lower portion. From the top of this swelling the stalk 

 diminishes gradually in thickness, assuming its smallest diameter about the middle of the 

 whole length, and enlarges slowly ujs wards, forming finally the upper enlargement at a 

 short distance below the polyps. The upper swelling is flattened nearly to the point 

 where the polyps are attached, and only in their immediate neighbourhood becomes 

 more cylindrical, so as to form a kind of short peduncle for their attachment. 



The polyps form a compact bunch, and seem to be placed all on one level. On a 

 closer inspection the axis is seen to run into the base of one of them, and here a kind 

 of short rachis is formed, which, however, is very different from the ordinary structures 

 of this kind. The real arrangement of the polyps is such that the nine polyps visible 

 from the outside surround a small inner area, which may be regarded as the dorsal side 

 of the rudimentary rachis, and from the middle of this space one single full-grown central 

 polyp arises, surrounded at its base by large wart-like zooids, which I am inclined to 

 interpret as rudimentary polyps. 



The zooids are very numerous on the upper part of the flattened enlargement, and 

 leave only the two middle lines free. They then advance towards the bases of the 

 polyps in such a manner as to form four pointed areas corresponding to the intei'spaces 

 between them. These pointed areas, which are visible to the naked eye, appear to 

 have been seen also by Ellis, and are figured by him at letter N. On the lower part 

 of the upper enlargement of the stalk the zooids become less numerous, and, so far as 

 I have been able to ascertain, they at length disappear, but they reappear on the lower 

 swelling of the stalk and in its neighbourhood, where they seem to be pretty numerous, 

 and to be arrayed in longitudinal lines. But I am not in a position to clear up totally 

 their relations, as I could not destroy the only specimen of this interesting form. 



The eolom- of this Umbellula is different shades of brown. 



Length of the whole, 



Length of the polypiferous portion, 



Length of the upper swelling of the stalk, 



Breadth of the upper swelling of the stalk 



Length of the lower swelling, 



Breadth of the lower swelling. 



Breadth of the stalk in the middle, 



Length of the polyps, 



Length of the tentacles of the poly]is, 



Length of the bodies of the polyps, 



(Z')OL. CHALL. EXP. PART II. 1880.) 



7-40 nun. 

 50 

 85 



7 

 77 



6 



45 

 19 

 2G 

 B4 



