MENIPEA FUGUERIS. 
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being called Hippocrepia, or Horseshoe animals, because the tentacles are arranged in a shape 
resembling that of a horseshoe. It will be, perhaps, hardly necessary to apologize for the 
introduction of so many technical terms, the fact being that the minute dimensions of the 
objects have caused them to escape popular observation, and to depend for their nomenclature 
upon the learned and scientific. Still, the technical phraseology is never employed where its 
use can be avoided, and when circumstances render its introduction inevitable, its meaning 
and the reasons for its employment are always given. 
We now arrive at another family, the Cellularidse, where the general shape resembles that 
of the preceding family, but the cells, instead of being arranged round an imaginary axis, and 
so forming cylindrical branches, are arranged on the same pfiane. A magnified example of 
this family is the CellulaTia peachii^ so called in honor of the eminent naturalist, Mr. Peach. 
In a creature belonging to the genus Menipea, found in Tierra del Fnego, and termed from 
its habitat , Menipea fugueris, the curious “ operculum” closes or rather guards the mouth 
of the cell. In this genus it is in the form of a simple spike. This species is found at low 
water. 
The avicularium is an object which is set somewhere about the middle of a cell, and 
always upon its outside, and assumes various shapes in the different species of polyzoa. 
What may be the precise nature of the avicularia is at present rather a mystery, and no one 
can definitely pronounce them to be actual portions of the cell, or merely parasites that remain 
affixed to the same spot. In all cases there is a decided resemblance to the head of a bird, 
though in some species the similitude is closer than in others. Only one avicularium is to be 
found on a single cell, though many cells do not possess these strange appendages. 
By close examination, it will be seen that the avicularium can be roughly distinguished 
into three portions ; namely, a base by means of which it is attached to the cell, a rather large 
head, and a movable spine like the lower mandible of a bird’s beak. In those examples where 
the avicularium is seated directly upon the cell, the only movement is that of the lower 
mandible, which opens and shuts with a continual motion, as if it were a veritable head of a 
hungry bird snapping at its food. In those cases, however, where the base is lengthened into 
a neck, the entire head is endowed with motion, nodding up and down in the most lively 
manner, very like those wooden birds sold in the toy-shops, whose head and tail are alternately 
raised and depressed by means of strings and a weight. But whether the head moves, or is 
still, the jaws continually open and shut, and will often inclose between their parts any small 
worm that may happen to come across their path, and have even been known to seize each 
other in their grasp. 
When the beak has seized a victim, and the mandibles closed upon it, they retain their 
grasp with astonishing tenacity, and when, as sometimes happens, two avicularia have seized 
the same worm, the unfortunate victim is rendered entirely helpless by the grasp of its foes. 
The purpose of these objects seems to be rather dubious, but two conjectures have been 
offered, which at all events are worthy of notice. 
According to the opinions of some observers, the avicularia answer the purpose of police, 
and force intruders to leave the spot where their presence might do harm to the creature on 
which they are placed. This duty seems, however, to be performed by the vibracula, and we 
must search for another theory for the true object of the avicularia. Mr. Gfosse has put 
forward a conjecture which is not only highly ingenious, but bears with it the elements of 
probability. 
“ More than one observer,” he remarks, “has noticed the seizure of small roving animals 
by these pincer-like beaks, and hence the conclusion is pretty general, that they are in some 
way connected with the procuring of food. But it seems to have been forgotten, not only that 
these organs have no power of passing the prey thus seized to the mouth, but also that this 
latter is situated at the bottom of a funnel of ciliated tentacles, and is calculated to receive 
only such minute prey as is drawn within the ciliary vortex. I have ventured to suggest a 
new explanation. 
“ The seizure of a passing animal, and the holding it in a tenacious grasp until it dies, may 
be a means of attracting the proper prey to the vicinity of the mouth. The presence of 
