176 BULLETIN OF THE 



animal This vibratile plate is homologous with the vibratile combs, of which 

 it is the exact continuance. The bright crimson pigment spots found in a row 

 at its base and along the auricles are probably functional, but, w^hether sensory 

 or not, has not been determined. 



From the origin of the tentacle to the angle formed by the oral lappets and 

 a ridge from the auricular appendages, Plate VIII. tig. 10, there passes a row of 

 small teutacula-like bodies, which closely resemble the filaments or secondary 

 appendages to the rudimentary tentacle. They resemble closely the tentacles 

 foung along the bell margin in Aurelia (Plate VII. fig. 6). Folds in the walls 

 of the intestine near the upper end of its course are well marked. These struc- 

 tures are figured in Bolina by Mr. Agassiz. 



The upper part of the funnel and the otocyst of M. Leidyi is figured in Plate 

 VIII. fig. 6. The bundles of nerves which pass fi"om the ganglion beneath the 

 otocyst distribute nerves to all the important organs of the body. Their course 

 can be traced very well, even to the margin of the oral lappets. They are un- 

 branched, and of a white, almost silvery color. Their course in a small portion 

 of the inner surface of the oral lappets has the appearance shown iu Plate VIII. 

 fig. IL There is in the adidt no circumscribed aborally placed sense organ of 

 dumb-bell shape similar to what has been mentioned in the young, Plate VIII. 

 fig. 5». A part of the body walls around the otocyst has a granulated appear- 

 ance, which may represent this structure in a reduced form. 



The otocyst is a two-layered sac containing otoliths arranged in a cluster. 

 This sac is without apical opening. The connection of the otoliths wdth the 

 ganglion is through the walls of the floor upon w^hich the cluster rests, and not 

 by suspension from the upper walls of the capsule. Four bundles of nerves 

 arise in a symmetrical manner from the ganglion, two of which are well 

 marked, and extend into the oral lappets, d, Fig. G. 



The network of lines on the inner walls and surface of the oral lappets is 

 arranged with great regularity, and does not form those characteristic spots, four 

 in number, which exist in Ocyroe maculata, Rang. Each line in the network is 

 made up of small cells, laid side by side. Nerve fibres are especially rich in 

 the oral lappets, which, as a result, are highly sensitive, quickly responding hy 

 retraction when the surface is touched. 



Cambridge, Februarj', 1881. 



