172 Prof. M'Intosh's Notes from the 



penetrating between the folds and rendering them more 

 distinct. The folds are directed obliquely outward and 

 forward, two on the pillars of the crown being more 

 nearly longitudinal than the others, and, besides, a patch of 

 tentacles closely abutting on the fissure lies to the inner side 

 of these. 



The tentacles are long and nearly cylindrical filaments 

 which in life often twist and wriggle about. When stretched 

 out they become attenuate, and distinct crenations directed 

 toward the tip occur on their ciliated edges, giving the organ 

 a transversely streaked aspect. Each contains two vessels, 

 apparently a single trunk bent upon itself at the tip, the 

 trunks looping together at the bases of the tentacles. The 

 fluid in these vessels is perfectly translucent and free from 

 granules. The matrix of the process is granular and pale 

 (hypodermic), and seems to keep the vessels from undue 

 pressure, yet retaining sufficient elasticity. Muscular fibres, 

 both longitudinal and circular, are also present, but the 

 latter were not distinctly seen. Under a power of 60 

 diameters the cilia of these organs are often seen to remain 

 perfectly still — projecting from the sides like minute glassy 

 spikes, then they suddenly are adpressed, the points directed 

 toward the tip of the tentacle. Occasionally they are jerked 

 in various ways — some vibrating rapidly a few times and 

 again becoming rigid. In the quiescent condition they bear 

 some resemblance to the spinous ray of a starfish or to some 

 spine-clad stems like Gleditschia. The tip of the tentacle is 

 more opaque than the rest, from its granules and gland- 

 cells, and now and then it assumes a clavate outline, and 

 in the preparations a few show a slight constriction below 

 the tip. 



On each side of the posterior groove of the mouth with its 

 glandular folds is a bifid process, the anterior rounded 

 portion of which is applied to the soft external fold of the 

 mouth, whilst the pointed and somewhat ligulate process 

 projects, like a ventral branchia, downward and slightly 

 forward. These organs probably act in conjunction with 

 the posterior buccal groove in tube-formation. 



The body is somewhat flattened, marked dorsally and 

 ventrally by a red streak. The cuticle is delicate and 

 iridescent dorsally between the branchiae, and is ciliated 

 especially over the sites of the blood-vessels. The dorsal 

 groove over the buccal region is also ciliated. On the 

 ventral surface opposite tlie 2nd and 3rd segments is a 

 smooth ovoid area clearly differentiated from the surround- 

 ing parts by an elevated border. 



