428 GEOLOGICAL SURVEY OF THE TERRITORIES. 
underlying cells, in fact they are prolongations of the latter. This 
change takes place in our Streptocephalus at a time when the eleventh | 
pair of branchipeds has made its appearance and 
the stalked eyes which laterally bud out of the head 
are already contracted behind and provided with 
Fig. 51.—Streptocephalus Fig. 52.—Right clasper ¢ Streptocephalus texanus Pack. oc. eye. 
texanus—right clasper ¢& 0 
larva 4™™ in length. : 
a stalk, while in Branchipus stagnalis the change in the second antenne 
takes place earlier. 
The three protuberances do not appear before the accumulated cell- 
masses have pushed out on the inner side of the antenne in a down- 
ward direction part of the main branch of the male forked clasper. At 
the time when the latter just begins to fork at its tip a second inner 
branch is budding near its inner base (Fig. 51). 
The remainder of the former second antenne grows out into the outer 
long flat branch of the clasper, but, as in the aquarium the full grown 
form is seldom reached, I could not closely follow the development of 
this outer branch in detail. The new clasper shows in its entire length 
polygonal cells in the integument, which, after another moult, have 
partly disappeared, being then permanently confined to but a few spots 
on the inner rounded corrugate sides of the same. 
Fig. 53.— 9 Streptocephalus tex- Fig. 54.—Cast-off skin of subimago-stage Strepto- 
anus, right clasper. cephalus texanus left male clasper from above. 
TI1.—LARVAL STAGES OF EUBRANCHIPUS VERNALIS VERRILL. 
\ 
During the whole summer of 1880 I experimented with dry mud from 
ponds inhabited by either the normal or pale race of this Branchiopod, 
but all in vain. Neither jars kept on ice in a large refrigerator, nor 
frozen, dampened mud, gradually or suddenly thawed, developed any 
larve. The mycelium of a fungus, a few Daphnide, and microscopie 
organisms were the usual result. 
However, I obtained a few early stages of the pale race and many 
specimens of the later stages of the normal form from the ponds them- 
selves. The latter are reddish and already pigmented when but 4™™ in 
length, while those of the pale race were dull white. 
Eubranchipus larve are comparatively much stouter and larger in 
their first stages than their allies. Larve of 0.8" in length with the 
first three branchipeds budded out and (osmic acid prep.) nine more 
