Plate XX. 



«..<?(/,, Anla,2;e of segmental duct. 



bp., blaRtopnre. 



hrg., brauchial region. 



cc, cloacal cavity. 



ed., collecting dnct. 



eh., chorda dor.salis. 



c.dv., div(irticnlnm of cloacal 



cavity. 

 co.sd., cloacal opening of seg- 



]n(Mital duct. 

 c.p., coolomic projection. 

 dl.hp., dorsal lip of blastopore. 

 fg., fore-gnt. 

 ep., epiblast. 

 (jc. genital cells. 

 liy., hypoblast. 

 ivt., intestine. 

 K, Anlage of liver. 



l.m., lateral plate of mesoblast. 

 well., mesenchymatons cells. 

 ms., mesoblast. 



m.jo., parietal layer of mesoblast. 

 rat.T, IT, &c., the first, second, &c. 

 myotome. 



m.V'., visceral layer of mesoblast. 



n., nenral canal. 



nd.Ô, fifth nephrostome. 



per it., peritoneal membrane. 



pp.l-S, ]ieritoneal partition. 



pp.c, plenro]ieritoneal cavity. 



pt.l-G, ])ronephric tubules from 

 the first to sixth. 



sch., Hul chorda. 

 sd., segmental dnct. 



yc, yolk-cells. 



Figs. 82-80. Sections from tlu^ same series as fig. 81, lying posterior 

 to it. The section shown in fig. 87 ])asses througii somewhat frontally 

 owing to the bending of th(^ body-axis of the embryo ; the neural canal, 

 which is Ijent in the sauK^ manner as tlie axis meets with two time 

 in section. 



Figs. 90 and i)L. Two sections passing through in the same way as in 

 fig. 87 ; in lig, 90 the dorsal li[) of the b1asto])ore, and in fig. 91, the 

 ni)p(n' (dorsal) ]iortion of it, is cnt through. 



Figs. 92-9f). Froui a series of transverse sections through a little older 

 embryo than the last ; the embryo is twisted in the same way as it. 



Fig. 97. Frontal section through an embryo abont the sam(^ stage as the 

 last, the bodv (»f which has been straightened befon^ cut throuiiii. 



