196 
PACIFIC SCIENCE, Vol. XVII, April 1963 
endo. 
~exa 
Fig. 1 . Hypothetical thoracic leg of Lepeophtheirus 
dissimulatus, showing the various armament compo- 
nents. C, Heavy setae; c, fine setae; endo, endopodite; 
exo, exopodite; f, membrane; H, well-developed spine; 
H', laterally projecting spine appearing as a continua- 
tion of segment; h, poorly developed spine; Hm, mem- 
brane margined spine; P, large plumose setae; P', large 
naked setae; p, small plumose setae; p’ , small naked 
seta; prot, protopodite; Q, seta (or spine) plumose 
on one side and membrane-margined on other; rh, 
spinule; s, hairlike seta; sp, sternal plate. 
Because of the failure of the culture material 
and in order to obtain a complete timed series 
of developmental stages, attached copepodites 
were taken from host material and placed in in- 
dividual stender dishes. After these copepodites 
moulted into the first chalimus (the following 
stage ) , the time was noted until the succeeding 
moult, into the second chalimus. To ascertain 
the time passed in each stage after the first 
chalimus, specimens of the previous stage were 
taken from the host and treated as above. Due 
to the mortality rate under laboratory condi- 
tions, many specimens of each stage had to be 
collected so that one would pass through the 
succeeding stage. Because of the inability to get 
any number of specimens to pass through each 
stage and due to the necessity of submitting the 
larvae to laboratory conditions, the time indi- 
cated for each stage in Figures 2-7 should be 
regarded as indicative, not conclusive. 
The descriptions of the body, appendages, 
and processes of all of the developmental stages 
and the adult is followed by a discussion of the 
general behavior of the various developmental 
stages. The graphical figures included in the 
text (Figs. 2-7) give the means and ranges of 
various measurements of the larval forms. 
Larval specimens other than nauplii were 
killed and preserved in 95% ethyl alcohol. Speci- 
mens to be dissected were placed in 85% lactic 
acid to soften and clear them, stained with 
methyl blue dissolved in 85% lactic acid, and 
dissected in clear 85% lactic acid. 
Drawings of the total animal were made from 
specimens placed in 85% lactic acid and cov- 
ered with a 9 mm cover slip. The cover slip 
was raised slightly above the younger specimens 
by thin pieces of glass so that the specimen was 
not distended. A camera lucida and a Bausch 
and Lomb arc projector were used to make the 
drawings of the total animal. Drawings of the 
appendages and processes were made, with the 
use of a camera lucida, from appendages and 
processes either in situ on the whole mount or 
dissected off and mounted in Hoyer’s mounting 
medium. Measurements were made with an ocu- 
lar micrometer. 
The terminology used, with some exceptions 
which are given in the text, is that used in 
Lewis (in press). To facilitate the use of the 
thoracic leg tables, a hypothetical thoracic leg is 
shown in Figure 1, giving all of the component 
parts of the armament of the thoracic legs dis- 
cussed in tabular form in this publication. Fur- 
ther, a table of the hypothetical thoractic leg 
is given below in Table 1. 
3.5 
3.0 
2.5 
£ 
.§2.0 
.c 
CD 
£ 1.5 
1.0 
0.5 
<D 
8 -mean 
t t 
if 
tt 
in 
L 
ft 
40 
"8*0 120 160 200 240 280 
Time in Hours 
Fig. 2. Greatest length of body, excluding setae, in 
developmental stages of L. dissimulatus. n, Nauplius; 
co, copepodite; ch, chalimus. 
