29Q M. Krohn on the Anatomy and 



almost regularly fusiform, growing narrow at its two extremities, 

 but particularly at its posterior extremity. At the anterior ex- 

 tremity of the body a head is readily perceptible. Five pro- 

 jecting appendages then strike the eye of the observer, extended 

 horizontally, and placed on the posterior half of the body : 

 these appendages have the form of leaflets or fins, and give 

 the animal, at first sight, some resemblance to a fish*. They 

 are attached to the body by a widened base, and diminish gra- 

 dually in thickness up to their margin, where they are very 

 soft and flexible. The hindmost of these fins, that which em- 

 braces the posterior extremity of the body, is an odd one : the 

 four others are arranged in pairs, that is to say, one opposite 

 another, on each side of the body. The posterior fin is triangular, 

 similar to the caudal fin of a fish, or rather, on account of its 

 horizontal position, comparable to the terminal fin of the Cetacea. 

 Each leaflet of the anterior pair of fins, placed almost in the 

 middle of the body, has the form of a segment of a circle, whilst 

 the two laminse which constitute the following pair, longer and 

 wider than the laminse of the first pair, resemble, up to a certain 

 point, a segment of a rhomb. 



The head is manifestly isolated from the body, and surrounded 

 by a kind of membranous hood, which the animal can draw 

 back, and which it does in fact draw back when it seizes its prey. 

 The upper surface of the head is placed on a level with the upper 

 plane of the body ; its lower surface, on the contrary, is oblique 

 from above downwards and from before backwards. When the 

 hood is in the state of the most complete expansion and brought 

 over the head, the latter is entirely enveloped in it, with the ex- 

 ception of its under surface, in the middle of which is seen the 

 mouth in the form of an elongated depression. When the animal 

 draws back this hood, the head, and particularly its sides, are ex- 

 posed, and the parts which 1 proceed to describe are perceived. 

 In front and on each side there is a simple row of horny hooked 

 prickles, arranged in a curved line, directed obliquely from above 

 downwards and from before backwards (these are the palpes stries 

 of MM. Quoy and Gaimard) ; they enable the animal to seize 

 and bruise its prey. Their number varies in difierent indi- 

 viduals from five to seven on each side. They differ from one 

 another in size ; the upper or anterior hooks being most fre- 

 quently shorter than the lower or posterior ones, which in their 

 turn are shorter than the three or five middle hooks. They 

 are very much flattened, but present a decided curve and a 

 pointed end. The base by which they are attached to the skin 



* For tliis reason the fishermen of Messina call this animal Spadella, — 

 the diminutive o^spada, a sword. 



