ADDENDUM ON NEBALIA. 85 



tail fringed with hairs and the styles of the tail annulate. 



To observe animals of this small size and concealed 

 character by simple inspection will not exactly answer the 

 purposes of Natural Science as at present pursued, we 

 must scrutinize, analyse and dissect, in order to determine 

 the number, use, and structure of the various members. 



Dr. Leach being the founder of this Genus, the first 

 Crustaceologist in Europe, and of the most scrupulous 

 exactness, we must naturally attach the greatest impor- 

 tance to the figure and description of Ncbalia whicli wo 

 have from his hands, bearing in mind that the parts of the 

 mouth remain to be dissected and made known. 



Description of Nehalia. 



The Cephalo-thoracic Clypeus, inclosing the body of 

 the animal is large, sub-compressed, and ovalish in its 

 lateral contour. 



The. moveable Rostrum or beak, which is one of the 

 most remarkable characters of Nebalia, is taper, carinated 

 above, and vaulted beneath. 



The Eyes are rather small, and situated at the sides of 

 the beak ; they are compound, placed on short footstalks 

 and moveable. 



The Antennce which arise on each side from above the 

 eyes, consist of a single pair, each ending in two pluri- 

 articulate setae. 



The Anterior pair of Feet are long and simple, serving 

 for prehension (and are probably armed with microscopic 

 hooks ?) 



The Posterior or Natatory feet consist of five pair, 

 having their ultimate divisions bifid and fringed. 



ITie Abdominal portion is composed of four or five joints, 

 and ends in a furcate tail, the two taper styles of which 

 end in setae. 



The Nebalia Herbstii of Dr. Leach attains to the length 



