Branchipus. 93 
and it is highly probable that it leaves the &%g in a more advanced 
stage of development. 
According to Dr. Claus the nauplius of B. stagnalis on leaving 
the egg is of a dull yellow {trubgelb) color, which has, as its cause, 
a multitude of bright granules and globules, and this color is so de- 
cided that for some time the view of the internal anatomy is ob- 
scured. The larva of B. venialis, on the contrary, is very pale, and 
will, therefore, more readily lend itself to investigations on the 
early condition of its internal organs. 
In the case of B. stagnalis the post-cephalic portion of the body 
is at first globular, but later becomes more elongated and oval,and 
finally, when the limbs have begun to bud out, changes to a conical 
form. The same portion of the body of B. vernalis is from the 
first proportionately shorter and broader. Furthermore, there are, 
in the earliest stages seen by us, the lateral buds of three or four 
pairs of post-maxillary appendages. The most striking difference 
between the larvae of the two species appears, however, to be 
found in time of appearance of the paired eyes. According to 
Claus those of B. stag?ialis do not appear until the first and second 
pairs of thoracic segments have become four-lobed and ten or 
eleven segments have been marked out. The larva of B. vernalis 
appears to possess both the median and the paired eyes at the time 
of escape from the egg ; at least the paired eyes are plainly visible 
in the earliest observed stages, when there are but the merest 
swellings to indicate the positions of the first four thoracic limbs. 
Thus the true nauplius condition of B. vernalis appears to be 
passed through before the larva escapes from the egg ; it is ex- 
cluded as a metanauplius. 
It is interesting to note that the larva which we saw endeavoring 
to escape from the ruptured egg-shell was enveloped in a thin 
transparent membrane. Whether this was the inner egg-membrane or 
a blastodermic moult we do not undertake to say. Zaddach's ob- 
servations on Apus will be recalled in this connection. {De Apo- 
dis cancriformis, 1841). 
Our smallest larvi^ measured in length fi inches. 
II. Description of a supposed 7iew species of Branchipus, B. Geli- 
i>^s. Male conforming closely to the description of B. bundyi, 
Forbes^ except that the caudal stylets are linear-lanceolate instead 
of broad and blunt. Frontal appendages long and narrow. Clas- 
Illinois M useum Nat. Hist., Bulletin No. i. p. 25. 
