BigELow. — Development of Lepas. 
PLATE 12. 
Lepas fascicularis. 
The figures in parenthesis following the descriptions refer to corresponding 
stages of L. anatifera. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Lit. 
112. 
113. 
114. 
115. 
116. 
ibys 
118. 
119. 
120. 
121. 
122. 
123. 
124. 
125. 
126. 
Horizontal section of sixteen-cell stage. (Compare with Fig. 43.) 
Sixteen-cell stage viewed from vegetative pole. Fifth cleavage. (Fig. 
46.) 
Same stage, seen from left side. (Fig. 45.) 
Thirty-two-cell stage viewed from animal pole. (Fig. 55.) 
Same stage seen from /eft side. (Fig. 53.) F 
Same stage viewed from the vegetative pole. Primary mesoblast 
(d5-2) and entoblast (d®1) in fifth cleavage. (Fig. 48.) 
Egg in same stage, looking upon the posterior pole. 
Sixty-two-cell stage seen from /e/t side. 
Same stage. Sagittal optical section seen from left side. Primary 
mesoblasts still in sixth cleavage. (Fig. 56.) 
Same stage. Horizontal optical section seen from animal pole. (Fig. 
64.) 
Sixty-two cells. Primary mesoblasts have completed sixth cleavage, 
being now four in number (d7°-d7*). Two entoblasts. 
Profile of late stage. Formation of dorsal transverse furrows (1, 2), 
which mark off the three metameres. Seen from /eft side. (Fig. 91.) 
Somewhat later stage seen from /eft side. Appearance of a third fur- 
row superficially subdividing the posterior (mandibular) metamere. 
Still later stage seen from /eft side. Another furrow subdivides the 
anterior (first antennary) metamere. (Fig. 93.) 
Dorsal view of same stage showing the longitudinal and transverse 
furrows, which, growing ventrally, fold off the appendages. 
Nauplius after development of paired appendages and beginning of the 
labrum. Seen from the /eft side, ventral being up. 
