292 J- Playfair Mc Mükrich, 



being attached to a barnacle shell and to the stems of a large 

 liydroid. 



The columii wall shows distinct long-itudinal ridges due to 

 elevations of tlie outer surface of tlie mesogloea. These, in the 

 individuals examined, while not arranged with perfect reg'ularity, 

 are not so irregulär as might be imagined from the Statement of 

 KwiETNiEwsKi; for the most part they do correspond to the intervals 

 between the insertions of tlie mesenteries, the figure which I gave 

 in a former paper (1893, tab. 21, fig. 19) representing the arrange- 

 ment which I find in the present specimens. 



The diso in the expanded individuals is smooth and concave, 

 the peristome usually forming a distinct elevation in its centre. 

 The mouth is oval or in some cases almost circular in outline and 

 the lips are ridged; no distinct gonidial grooves oceur. 



The tentacles are arranged in two sets, a peripheral or mar- 

 ginal set arranged in two cycles and a disc set arranged in radiating 

 rows upon the disc, the various tentacles of each row communicating 

 with the same endocoel. In two fully expanded individuals it was 

 possible to determine the exact arrangement of the tentacles, which 

 was as follows. The peripheral tentacles were arranged in two 

 cycles, the members of the outer circle being as a rule smaller and 

 directed outwards, while those of the inner cycle were larger and 

 usually directed almost vertically upwards. Of the inner cycle I 

 counted in two cases thirty-one and in another case twentj^ three(?) 

 tentacles, but I was not able to satisfy myself as to their relations 

 to the mesenterial Chambers and nmst accept Kwietniewski's State- 

 ment that they correspond to exocoels. 



The disc tentacles are situated on the radii from wliich the 

 outer cycle of marginal tentacles arises and on these alone, and two 



sets may be recognized altern ating regularly 



with one another. In one set each radial 



row consists of three tentacles and in the 



other of only two, so that, taking into 



account the marginal tentacles there will 



be in a sector of the disc, flrst, a radius 



containing a row of four tentacles, then one 



Fiff. B with only a Single tentacle, then one with 



three and then another with one, and this 



succession is repeated all round the disc, although occasional ir- 



regularities may result from the failure of some of the tentacles of 



