VIVIPAROUS FISHES OF THE PACIFIC COAST 
477 
Plate CXI. 
Figs. 138-143. A series of six sections through a similar larva as that represented in fig. 136. 
Fig. 138. Through the auditory vesicle and first gill-slit. 
Fig. 139. Through the posterior part of the branchial region. 
Fig. 140. Through the middle of the yolk. 
Fig. 141. Through the posterior part of the yolk and the yolk vesicle. 
Fig. 142. Between the yolk and. the anus. 
Fig. 143. Through the anus. 
Plate CXII. 
-149. Sections showing Kupffer’s vesicle. 
Sagittal section through the end of a larva in which the neurenteric canal persists, ending 
in a small vesicle in the neural chord. There is apparently an anterior and a posterior 
canal. These probably represent the anterior and posterior margins of the primitive canal, 
thj space having become partly filled with cells. 
Sagittal section, showing continuation of endothelium of intestine over Kupffer’s vesicle. 
A later stage, showing Kupffer’s vesicle in connection with the alimentary canal, the neu- 
renteric canal, and the yolk vesicle. 
Kupffer’s vesicle reduced by the formation of a thick cellular floor. 
Sagittal section through the tail of a larva 0-85 inch long. The vesicle has been reduced. 
In the region it formerly covered the cells are much more loosely arranged than elsewhere. 
The space in which cells or nuclei are seen in neighboring sections has a sharp outline. 
A canal extends from the remains of Kupffer’s vesicle upward to the neural canal. The 
vesicle has been greatly reduced. 
Plate CXIII. 
Figs. 150-154. A series of horizontal sections of a larva, 1-8 mm. long, the region in front of the chorda 
being bent nearly at right angles to the main axis ; the sections in front of this region are 
cross-sections. The hypoblast is shaded. 
Fig. 150 passes just above tho opening of the hyobranchial slit. The chorda is cut obliquely. 
Fig. 151 passes through the hyobranchial slit and also through the spiracle ( spi ) or hyomandibular 
slit, which is seen to greatly resemble the bars and slits behind the hyobranchial. 
Fig. 152 passes through the anterior end of the notochord, and the hypoblast is seen to extend up at 
this place so that it is in contact with the chorda. Laterally, the section passes through 
the spiracle and the hyobranchial slit. A layer of flat epiblast cells is seen to extend into 
the opening for some distance. 
Fig. 153 is four sections farther forward and shows the restricted hypoblast. 
Fig 154 is two sections farther forward and passes through the posterior portion of the right eye. 
Just beneath it the hypoblast is seen to extend out to the epiblast, and this is the fundament 
of the right half of the mouth. The similarity between this and the spiracular hypoblast 
of fig. 153 is very striking. In neither case is there any evident ingrowth of epiblast. 
Plate CXIV. 
Figs. 155-160a represent a series of cross-sections of a larva 1-8 mm long. 
Fig. 155. The section passes through the upper posterior part of the hyobranchial slit and the lower 
anterior part of the second branchial slit. The section is at right angles to the one repre- 
sented in fig. 151 at the point br 1. 
Fig. 156. Three sections farther back, through the first and second gill-slit on the left, through the 
third on the right. 
Fig. 157. Behind the third gill-slit on the left, near the end of the gill-thickening on the right. 
Fig. 158. A short distance behind the pronephros, the liver forming below, the air bladder above; the 
pectoral plates are noticed on the sides. 
Fig. 159. Through the alimentary canal at the rudiments of the liver. 
Fig. 160. The same farther back. 
Fig. 161. Through the hind gut of another larva in the same stage of development. 
Fig. 161a. Outline of a section through the anus not so highly magnified. 
Figs. 144- 
Fig. 
144. 
Fig. 
145. 
Fig. 
146. 
Fig. 
147. 
Fig. 
148. 
Fig. 
149. 
