360 CARL VOGT. 



dermic layer extends througliout the entire length of the arm. 

 Prom this layer the large, pale, slightly granular cells [g] which 

 support the whip-like vibratile cilia, are readily distinguishable ; 

 they are ranged in two rows. There are indications which seem 

 to show that the cuticle is continued over the inner surface of the 

 tentacle. Besides the large whip-like organs, there are delicate 

 vibratile cilia distributed over the internal surface of the hood 

 between the tentacles. 



The movements of the cilia are controlled by the will of the 

 animal ; when the tentacles are folded in, they may be seen to 

 execute very slight, undulatory movements, whilst they play with 

 perfect regularity when the tentacles are expanded. The move- 

 ments of the latter seem to the author to depend on those of the 

 hood. No contractile tissue has been noticed in the tentacles, 

 nor any muscular fibres. The author has been unable to verify 

 Kowalewsky's observation of longitudinal fibres at the base of 

 the arms {\\\ Loxosoma Neapolitanum) . Nor has he detected any 

 cavity or internal canal, the whole space within being filled by 

 the cells. Schmidt regards the tentacles as tubular, and believes 

 that they are elevated by the injection of flaid into the cavity. 

 Any such mechanical arrangement the Author considers to be 

 simply impossible under the circumstances. Even if the structure 

 of the tentacle itself were such as to admit of it, it would be 

 necessary that this cavity should be in communication with a 

 space, capable of being contracted or compressed, when the arms 

 were to be raised, and again expanded when they were to be 

 lowered. Iii fact, however, the tentacles are only in connection 

 with the vestibule, which is always more or less open, and most 

 widely open when the arms are raised. It appears, therefore, 

 that they must be elevated by the relaxation of the sphincter ; 

 that being attached to the hood by their external surface, they 

 are drawn outwards when it opens, whilst they are bent inwards 

 as it contracts. The vermicular movements, to which allusion 

 has been made, seem to depend on contractions of the cells 

 themselves, especially of the hypodermic cells, which are strongly- 

 developed on the tentacles. 



The Digestive Canal. 



This portion of the structure is most readily examined in young 

 individuals, in which the parts are not concealed by the growth 

 of the generative organs. The author was much assisted in his in- 

 vestigations by feedmg the polypides with carmine, an antiquated, 

 but very serviceable practice. The mouth {i, PI. XXII, fig. 5) 

 is placed on the median line, at the base of the tentacular corona, 

 on the ventral side. It is in the form of a very wide funnel, 

 with thick and solid walls. Viewed in profile, this funnel- shaped 



