Eig. 6. The hare patch along the course of the umbilical vessels of left cornu of
the chorion of Orcella, drawn of natural size: r., right and I., left pole;
d., dorsal or anterior and v., ventral or posterior margin; p., peduncu*
lated body.
„ 7. The surface of the chorion of Platanista, exhibiting bare patches, vascular
elevations and villous membrane, about natural size.
„ 8. One of the chorionic bare spots and surrounding villous membrane also of
Plata/nista, enlarged 4 diameters.
„ 9. The internal uterine surface of Platanista demonstrating its mucous membrane,
with scattered irregular sized bare patches. Natural size.
„ 10. A single bare spot of the preceding specimen enlarged 4 times: the orifice
of a utricular gland is seen in the middle.
PLATE XXXVI.
Various microscopical sections exhibiting intimate structurent the skin, teeth,
eye, stomach and umbilical cord of Plata/nista ga/ngetica and Orcella brevirostris—
Eig. 1. A piece of the cuticle of Platanista as seen from below, under a 2-inch
object glass.
„ 2. A vertical section of the skin of the foetal Platanista from the upper jaw
around one of the hairs (the latter being an appendage of a temporary
kind): p., papillary layer; c., coarse connective tissue, containing fat
globules ; f m., strong fibrous and partially muscular layer with abundance
of fatty and oily tissues ; A , hair o t rudimentary bristle with
firm tissue around, and cut somewhat obliquely ; v., a large vascular
space. Magnified about 15 diameters.
„ . 3. A vertical section of the skin of the snout of the young P . ga/ngetica
enlarged about 6 diameters : p., papillary layer ; <?., coarse connective
tissue ; b., layer of blubber, composed of masses of fat cells intermixed
with coarse fibrous tissue ; jf., layer of coarse fibres and finer connective
tissue almost devoid of fat globules ; m., muscular layer, the bundles
being cut obliquely.
„ 4. A view of a portion of a transverse vertical section of the lower jaw with
non-errupted tooth in situ : d. g., the dental groove, here, however, shown
as if opened at the top ; ep., epithelial lining of same, and in continuity
with (s.), skin of gum; <?., connective or fibroid tissue of the deep skin
textures ; e., enamel layer of tooth reaching quite to its base ; d., dentine
only partially developed above, and imperceptibly blending with
the pulp, the latter exhibiting no traces of cement or osteo-dentine ;
c. A, large meshwork of cancellated bone tissue, here only yet in process
of formation ; v., vessels supplying capillaries to bone and tooth pulp ;
n., nerves immediately above. Enlarged about 5 times.
I
I j
I
Eig. 5. A magnified view of a special section of a tooth of a young Gangetic
Dolphin. I t shows a complete enamel (<?.) layer, and the centre composed
of characteristic dentine (d).
6. Adult tooth of Platanista, from the middle of the lower jaw, in vertical
section. About twice natural size.
7. Ditto of a tooth behind the middle x 2 diameters.
„ 8. Ditto from the posterior third of the row, about 2 diameters. In the
three last figures e. signifies enamel; d., dentine; and o. d., osteo-dentinel.
„ 9. A thin transparent longitudinal, vertical section of the eye-ball and
surrounding soft textures of a full grown Plata/nista, and of natural size.
,, 10. The same section enlarged about 6 times and showing the various parts
as f o l lo w s 6., eyelids, with thick pigmental papillary skin covering
; m., cut muscular fibres of the palpebrse, imbedded in firm fibrous
tissue; c., cornea and its conjunctival covering; a., aqueous chamber;
v., vitreous chamber and humour; I., position which the lens should
occupy; i., iris; ch., choroid coat; s., sclerotic; op., optic nerve; f., fatty
envelope of eye-ball; g., gland.
,, 11. A transverse section of the umbilical cord of Platanista, enlarged twice
natural size: a., arteries; v., one of the umbilical veins; u., urachus;
g. b., glandular body; v. s., vascular spaces.
„ 12. Vertical section through the wall of the first cavity of the stomach of
P. ga/ngetica, enlarged 4 times natural size.
„ 13. A strip of the same vertical section of first stomach more highly magnified:
ep., epithelial layer; g., glandular layer; c., connective tissue layer or
submucous coat; m., muscular layers; fs., fibroserous coat; v., bloodvessel.
„ 14. A vertical section through a portion of the wall of the first gastric cavity of
Orcella brevirostris: ep., epithelial layer; c. g., columnar layer or mucous
glandular layer; c., connective tissue of submucous coat x 10 diameters.
„ 15. Vertical section of the wall of the second gastric cavity of Orcella: g.,
glandular layer; <?., connective tissue or submucous .coat; a., thick-
walled arteries piercing same, and shown both in transverse and deeper
in oblique section. Highly magnified.
„ 16. An enlarged view of portion of a vertical section of the pale piece of the
ductus communis choledochus of O. brevirostris, about 20 times natural
size: g„ glandular and epithelial layer; c., layer of connective tissue
(submucous coat); m., muscular layers; fs., fibroserous investment.
PLATE XXXVII,
Microscopical structural peculiarities of the glands of the stomach, the lungs,
the larynx, thp female genital organs, and placenta of Orcella and Plata/nista
Eig. 1. A vertical section of a small piece of the upper layer of mucous membrane