Fig. 1. 
(92) 
Fig. 2. 
(91) 
PLATE XL. 
P.{aralichthys| oblongus. [bc = blastocoele; ep = epidermis; pb = periblast]. 61 sec- 
tions. This figure is the twenty-fifth [of sixty-five sections] and is like the middle ones. The 
periblast is thin but extends farther under the cap than in Fig. 2. Near the center the layer 
fades out and is not recognizable, but four nuclei are very distinct, showing that the layer exists 
though thin and perhaps not fully differentiated. The nuclei extend under the entire cap 
although the ring has scarcely begun. 
This shows that the periblast has already begun to expand as an independent layer and has 
therefore probably ceased to contribute directly to the cap. 
P. oblongus. [be = blastocoele; ep = epidermis; pb = periblast]. Three hours after 
32-cell stage. Four of sixty nearly longitudinal sections. Left end = embryonic region. 
The second section does not reach cap; third touches cap. 
The fourth section shows some of cap, and periblast thinner at middle. 
The eleventh section shows periblast still thinner in middle. Nuclei are more numerous at 
left end all through these sections. I think the periblastic nuclei are more numerous under 
region of embryo than elsewhere. 
On the seventeenth section the periblast is scarcely visible at center beneath cap. On the 
sixteenth two nuclei were found near the middle of the subgerminal plate, although the plate 
is scarcely traceable. 
One nucleus was seen near middle of the nineteenth section and one in twenty-fourth. 
The periblast is somewhat less in bulk on the middle sections than on the thirty-eighth which 
I have drawn. Periblast is here about same in quantity as in Fig. 2, Plate XX XIX. (Three 
hours after 32-cell). 
