NOCTILIJCA MILIARIS. 9 



irritating substance like Ammonia be added, the tail, or tentacle 

 is seen in rapid motion, and the light flashes out with great 

 rapidity. This tentacle is extremely brittle, breaks with a short 

 fracture, and is evidently composed of rings of spiral tissue. 

 Dr. Webb states that he has never seen any restoration of this 

 part should it be lost, and on the death of the creature it coils up ; 

 but I should add that even after the partial rupture of the invest- 

 ing membrane, and the discharge of its contents, he has seen it 

 vibrating most vigorously. A very shallow cell in an ordinary 

 glass slip is the most convenient method of examining the 

 motions of this organ as it swims towards the under surface of the 

 glass. The powerful uses for which this tail is employed require 

 undoubtedly that it should be composed of strong muscular fibre. 

 There is, however, a considerable measure of doubt as to whether 

 or no there is any opening, or mouth, at its extremity. 



The body itself is composed of a dense external membrane, 

 continued on to the tentacle, and underlying this is a gelatinous 

 membrane, throughout which minute granules are indiscriminately 

 scattered. From this membrane arises a network of very delicate 

 fibrils, possibly not more than one three-thousandth part of an 

 inch in diameter, and these passing internally, become more open 

 till they are merged into coarser fibrils, which converge toward the 

 stomach and nucleus. All these are covered with granules, which 

 are generally larger toward the centre. Quatrefages thinks that 

 these granules move with the contraction and expansion of the 

 membrane in which they are embedded. Supposing that we are 

 viewing the animal in front, the oral aperture will be found on 

 the right side of the groove, a little distance below the tentacle, 

 which is on the left. This mouth-like organ appears in the 

 character of a short oval tube, consisting most probably of striated 

 muscular fibre, leading into the granular mass of the alimentary 

 canal, and from this latter the fibres and fibrils radiate. Near the 

 point of insertion of this oral aperture there is always a mass of 

 sand and other substances adhering with greats tenacity to a semi- 

 granular material, with a hernia-like projection, and this substance 

 is continued internally in much larger proportions. There appears 

 to be an utter absence of anything like a digestive canal, but in 

 the middle of this granular matter there are more frequently 



