Fcetal membranes of Lagenorhynchus and Orca, 



Fig. 1. Vertical section through the chorion fætalis of the 75 miilim. long ovum of Lagenorhynchus acutus, Gray 

 (see PI. VI, fig. 1). E = chorionic epithelium; B = connective tissue coii^isting of two layers with elongated, 

 oval cells; M = mesenchyme, with fibrils of connective tissue here and there: it contains capillaries, a few small 

 veins and some wandering cells. Vc = that part of the mesenchyme in which vacuole-like spaces occur; Jf ^ 

 a more indifferent mesenchyme, with a few veins and wandering cells. The dotted lines, which appeal' like red 

 points in the carmine-coloured specimen, probably arise from deposit of thicker albuminous matter. 



2. Section of the allantois from the same ovum (which contained the 8 miilim. long embryo of Lagenorhynchus 

 acutus. Gray). The contour lines drawn with an Abbes drawing-prism, Zeiss Obj. BB. Oc. 2. The section shows 

 a narrow lumen, the cavity of the allantoic sac, a.l, in which the epithelium, a.e, is detached from the connective 

 tissue basis, ab. The peripheral tissue, a.d, consists of spindle-shaped tissue cells, m = the easily-coloured 

 intercellular substance. 



.'i. Section of the chorion fætalis of the 4.5 miilim. long fætus of Lagenorhynchus acutus, Gray; drawn with 

 Abbes drawing-prism, Zeiss obj. a* oc. .3. The section shows a villous chorion with simple epithelium, E, which 

 rests upon a thin layer of connective tissue, beneath which is a narrow portion of mesenchyme, M, bounded within 

 by the allantois, .4/?. 



4. Section through a thickening of the wall of the vesicula umbilicalis (PI. VI, tig. 6). i = interior, with 

 coagulated masses of albumen : <' = exterior ; v = wall of vesicle ; /' = thickened portion of the wall of vesicle ; 

 pr = proliferous tissue cells; k = vessels; o m = lumen of ductus omplialo-mesentericus with epithelial 

 tegument, ep. 

 „ 5. Transverse section of the chorion from one horn, from the 408 miilim. long ftetus of Orca gladiator. Natural 

 size. Ch = chorion, with numerous longitudinal folds and small villi; (tU = allantoic cavity; am = amniotic 

 cavity; ms = partition wall formed by the allantois and amnion, where they touch each other; v = transverse 

 section of vessels in one corner of the partition wall. 

 „ H. Section of the chorion from the above named fretus of Orca gladiator, drawn with an Abbe's drawing-prism, 

 Zeiss obj. a* oc. 2. The villous excrescences of the chorion are visible with their simple epithelium, ve = villous 

 excrescences; e = chorionic epithelium; h = connective tissue; in = mesenchyme; I; k = small vessels and 

 capillaries in the villi: //A-" = transverse section of larger vessels; nil = allantoic cavity; «»« = amniotic cavity. 



(Figs. 1, 5 and 6 are drawn by Olaf Bergh, medical student; figs. 2, 3 and 4 by the author, G. Guldberg). 



