
(E275 4) 
XIV.—On the Placentation of the Seals.* (Plates XVIII.-XX]I). 
By Professor TuRNER. 
CONTENTS. 
} PAGE PAGE 
: rodttetion, ; ‘ 275 Comparison of the Placentation of the 
Description of the Uterus aiid Blac, ; 276 Seals with that of the Carnivora, . 290 
On the Appearance of the Fcetus, : 288 
Observations on the form of the Placenta and on the arrangement of the 
Foetal membranes in the Seals have been recorded by more than one anatomist. 
ALESSANDRINI of Bolognat obtained a specimen of the Monk Seal (Phoca bicolor) 
Monachus albiventer, in the gravid condition, in which the uterus contained 
a single foetus. He recognised the placenta to be zone-like in form, as in 
the Carnivora. He also described a decidua surrounding the margin of the 
placenta, and gave many particulars respecting the arrangement of the chorion, 
the allantois, the amnion, the umbilical vesicle, the umbilical cord, and the 
general mode of distribution of its blood-vessels. RosrenTHAt stated{ that in two 
pregnant seals, which he dissected, the placenta was zone-like, as in the cat and 
dog, and that each uterus only contained a single foetus, as is the rule, he be- 
lieves, in this group of animals. EscuricuT considered§ that the examinations 
which he had made of the membranes of seals preserved in spirit of wine were 
confirmatory of the correctness of ALESSANDRINI’S observations. Barkow 
described|| the dissection of the uterus of the common seal, Phoca vitulina, in 
which he saw a zone-like placenta. Only a single foetus was present, and that 
in the left uterine cornu. Although the right horn was far from equalling in 
size the left, it was considerably larger than in the non-gravid condition, and the 
uterine glands were strongly developed in its mucous membrane, but there 
was no extension of the foetal membranes into it. He also pointed out that 
the ramifications of the umbilical vessels extended as far as the ends of the 
chorion. 
* The substance of this memoir was communicated orally to the Royal Society of Edinburgh, June 
2, 1873, and a brief abstract was published in the “Proceedings” of that date. Through various 
causes its expansion into a form suitable for the Transactions of the Society has been delay ed much 
longer than was at the time contemplated by the author. (June 1875). 
+ Opuse. Scientif. vol. iii, 1819, and Meckel’s Archiv. vol. v. p. 604. 
{ Zur Anatomie der Seehunde. Nova Acta Caes. Leop. Akademie XV. 1825. 
§ De Organis, &., p. 19. Hafnie, 1837. 
|| Zootomische Bemerkungen. Breslau, 1851. 
VOL. XXVII. PART III. 4C 
