BIHANG TILL K. SV. VET.-AKAD. HANDL. BAND 95. N:0O 18. 11 
the anterior antenne. This being the only difference between 
the two forms, it may be sufficient to describe the larger of them. 
Nauplius: (P1. III.) Body transversal, rather high and 
convex, bearing three pairs of developed limbs, and two 
rudimentary ones, represented by sete. First pair, from 
which the anterior antenn&e apparently arise, least developed, 
very short, obtuse and quite destitute of joints. They are 
very distant from each other in the middle, but scarcely 
visible outside the anterior margin ofthe body; their posterior 
margin going backwards and meeting the margin ofthe large 
mouth-shield or upper lip. Antenne having two larger 
spinous sete at their anterior margin, two simple sete at 
the apex itself, a singular cirrus and a seta at the posterior 
margin. Second pair of limbs much more complex, con- 
sisting of four different parts or branches: 1:o a dentate 
process, directed inwards, moveable backwards and forwards 
under the mouth-shield and bearing a small secondary branch 
in the curve ofthe outer side; 2:o a slender branch, situated 
next to the outside and a little behind the preceding, with two 
sete at its apex, both these branches in the natural state of the 
animal slightly standing out from the body, at least not 
more than the mouth-shield itself; 3:o a short, but stout part, 
bearing a strong elaw and some sete at the apex, this part 
standing out almost perpendicularly from the lower surface 
of the body, but not visible outside its margin; 4:o alonger 
branch, being the outmost, bearing four spinous sete at the 
apex, and situated for the most part outside the margin of 
the body. 
| Third pair of feet simpler, consisting of only a elawed 
piece rather resembling the third branch of the preceding 
pair of feet, but larger and bearing a tubercular process with 
three set&e at the outer margin, four set&e at the base of the 
claw on a lamelliform lobe, and lastly a small spinous se- 
condary branch on the inner side. This pair of feet also 
stands out very much from the lower side of the body. 
Behind it there is on each side a spinous seta on a tubercle, 
and between these in the middle of the posterior part of the 
body there are moreover two broader elevations, bearing 
two spinous and one simple seta. This pairis missing in the 
first stage of development and is consequently younger than the 
other, although the latter is less developed. The appearance of 
