Collected by the late Dr. J. I. Northrop. 183 



band of brilliant yellow, and the tentacles have the appearance 

 of white glass. 



The mesogloea of the column walls is rather thin and in much 

 contracted forms may appear as if provided on its endodermal side 

 with numerous distinct processes, which give to the column wall 

 a ridged or chequered appearance. Toward the upper part of the 

 column are numerous cinclides, not readily distinguishable in all 

 preserved specimens and apparantly without any very definite ar- 

 rangements, though they are confined entirely to the upper part 

 of the column, none being found below the middle. 



There is a distinct collar and fosse in the preserved specimens 

 just above the cinclidal region of the column, and at that portion 

 of the wall which forms the floor of the fosse the endodermal 

 muscle processes are considerably higher than elsewhere in the 

 column wall, and form what may be termed a diffuse endodermal 

 sphincter. The true sphincter lies however higher up, just below 

 the point where the tentacles arise, and is a weak structure im- 

 bedded in the mesogloea, which is hardly appreciably thickened 

 for its reception. It consists of a few rather scattered cavities, 

 arranged practically in a single row and containing the remains 

 of muscle cells ; it is not strong enough to produce complete en- 

 closure of the tentacles. 



On account of the position of the sphincter the collar cannot 

 be regarded as the margin. Indeed there is no distinct margin, 

 the upper part of the column wall passing directly over into the 

 bases of the tentacles, so that, in the usual formula it is necessary 

 to say that the margin is tentaculate. The tentacles are rather 

 numerous, apparently somewhere in the neighborhood of 192, 

 though an acurate count is difficult in the preserved specimens on 

 account of the manner in which the cycles are crowded together 

 towards the margin. They vary somewhat in length in the 

 various specimens I have examined, owing to difflerence of 

 contraction, but the average may be put at 1 cm. The most in- 

 teresting feature of the tentacles is however the occurrence upon 

 them of a large number of spherical protuberances scattered over 

 their surface without any apparent regularity, though more 

 abundant upon the oral than on the aboral surfaces. In section 

 (PI. fig 1.) these are seen to be hollow outpushings of the wall of 

 the tentacles. The wall of the tentacle proper has a moderately 

 thick mesogloea, the ectodermal and endodermal muscle pro- 



