52 



funiculus umbilicalis. The amnion was of far greater extent than the allantois, the latter reaching not nearly so far out towards 

 the poles. The allantois occupies the concave portion of the horn of the uterus and is smaller than the amnion. — Turner 

 deduces very important physiological conclusions from his comparative examination of the Orca's fætal membranes with the 

 Ungulate forms of diffuse placenta. Thus he says (p. 501) "I am not disposed to consider that the utricular glands cease 

 to perform their functions at an early period of embryo-life. In this Orca, although the foetus has reached an advanced 

 stage of developement. the vascularity of the glands, their epithelial contents, even the presence of plugs of epithelium or 

 inspissated secretion projecting through their orifices, all gave one the impression of structures in a state of active employment. 

 If this be the case, then the secretion would be poured out into the crypts, and brought in contact with the villi of the 

 chorion.'" — In an able treatise (in Proc. Roy. Soc. Edin. 1875 — 76), in which the same author describes the fætal membranes 

 in the Narwhal (Monodon monoceros), the discoveries and conclusions previously made are confirmed. Concerning the chorion 

 of quite a small Narwhal foetus (.3 'A inches long) he remarks, that it ''was not villous, but traversed by faint ridges, which 

 without doubt fitted into the shallow furrows of the mucosa'". 



An interesting contribution to the knowledge of the fætus and tlie fd'tal membranes is moreover made by 

 Andersson (45), who, besides the external form, anatomy and habits of Orcella and Platanista, also describes their 

 gravid uterus, fætal membranes and embryos. He draws attention to the fact that there are several bare spots on the chorion 

 fd'talis in Platanista, where there are no villi. Tlie layer described (p. 491) as membrana intermedia, between the 

 chorion and the amnion, is probably the mesenchyme, which I have described below, as it attaches itself to the more difterentiated 

 thin layers of connective tissue, upon which the chorionic epithelium lies. The position of the fætus in the case described 

 by Andersson, was also in the left horn of the uterus, only with the snout up towards the end of the horn. In other 

 respects, Andersson's description agrees with the circumstances previously described by Turner as found in the Orca, so that 

 the fiotal membranes in these tropical species of Dolphin do not materially differ from the others. 



Further contributions are made by Beauregard and Boulart (47). who describe the mucous membrane of the 

 gravid uterus, and the fætal membranes of Balænoptera Sibhaldii. They for the most part corroborate what Turner has 

 already shown. Chabry and Boulart (48) describe a fætus of Delphin us delphis, L. with the fætal membranes, and 

 its position in the uterus, a description further corroborating previous discoveries. Hermann Klaatsch (55) describes at 

 some length the fætal membranes and their histology, (more particularly the structure of the umbilical cord), of a fætus of 

 Phocæna communis, Less., 60 centim. in length, to which are added remarks on the microscopical structure of the uterine 

 mucous membrane and the genitalia in the mother animal, and on the fætal milk-glands. He points out among other things, 

 the persistency of the ductus omphalomesentericus in the umbilical cord, and that in the Phocæna there is only 

 one hare spot on the chorion, namely, at the left pole of the ovum. 



From the facts already given, it is clear that as regards their fætal membranes, the Cetaceans must be placed 

 in the group, which embraces mammals with a diffuse placenta, and therefore approximate certain forms of Ungulates. Balfour, 

 (49), however (Traité d'Embryologie et d'Organographie Comparees, traduit par Eobin et Mocquard, Paris, 1885 ; vol. II), makes 

 the very plausible remark : "Les Cétacés different considérablement des Ongulés par la dimension de I'amnios et les faibles 

 dimensions du sac allantoidien persistant.'" — with which Max Weber (54) also seems to agree, as he, with full justification, 

 says; "Auf die Placenta allein hin die Cetacen zu Ungulaten zu raachen, witre gewiss unrichtig. Doch ist sie gewiss ein 

 Zeichen ursprlinglicher Verwandtschaft.'" To this he further adds, — and I am also of his opinion. — "'dass die diffuse 

 Placenta eine sehr primitive Form ist, und insofern gut iibereinstimmt mit dem primitiven Verhalten anderer Organe, die 

 Cetaceen . . . . zu einem generalisirten, collectiven Typus machen, der nur nach einzelnen Eichtungen hier in hohen Masse 

 specialisiert ist.'" 



After these remarks and quotations from the most important literature on this subject, I shall pass on to relate 

 the various facts I have elucidated from the material at my disposal. The figures illustrative of these will be found on PI. 

 VI and VII. It may be mentioned that Dr. F. Nansen drew the figs. 2 and 3 on PI. VI. For the interpretations put 

 upon the different facts given in the following, I (Guldberg) am alone responsible. 



Lagenorhynclms acutus, Gray. 



In the great take in November 1885 on Torskiien. whereby the Bergen Museum acquired a unique collection of 

 Lagenorhynchus acutus embryos, there was also taken out of a female animal an entire small ovum, in which the smallest of 

 the cuilji-yos described above, viz. 8 millim. in length, was lound. This ovum will now be more particularly described. 



As fig. 1, PI. VI shows, the ovum was oval, about 75 millim. in length in the hardened condition, and exhibited 

 a i)erfectly smooth surface without villi, a circumstance which agrees with Turner's description of the fætal membranes in the 

 small Narwhals f(etus (44). A few furrows running in different directions may perhaps be ascribed to the hardening process; 

 but in certain ])laces it shows larger natural folds and an incipient villus formation. 



