13 
Mammals generally. 
M. maxillo-labialis. Buccinator-group, 
14 
origin extends above the foramen infraorbitale. The two portions 
are fused into one; the part corresponding to the upper portion 
in the Dog is anteriorly split up into several strong tendons, of 
which the uppermost, and strongest, is inserted into the hinder 
end of the nasal cartilage; while the rest are inserted into the skin 
behind the nostril. That part of the muscle which corresponds 
to the inferior portion in the Dog ends fleshy, as in this animal. 
The m. maxillo-labialis of Talpa (PI. 15, fig. 1) is particularly 
interesting inasmuch as its origin has moved much farther back 
on the head than in any of the Mammals yet mentioned; the 
muscle arises from the skull above the bony ear-opening and ex¬ 
tends outside the zygoma between the m. temporalis and masseier, 
all three muscles forming together one muscular cushion on the 
side of the head. The muscle is composed of several narrow, 
loosely connected, muscle-bellies, which may easily be separated 
by dissection. One of them, which is, as it were, ensheathed by 
the others, is continued into a strong tendon, which goes to the 
upper side of the nose; at the posterior end of the cartilaginous 
nose this tendon is united with that of the other side and is 
continued as a flat ribbon onto the fore end of the proboscis. 
Of the other small muscle-bellies the lowermost is continued 
into the strongest tendon, which goes to the ventral side of the 
proboscis and ends not far from its tip near that of the other 
side (but separate). The rest, three in number, are also each 
continued into a long thin tendon, lying laterally on the pro¬ 
boscis and ending' towards its tip 1 ). (Comp, also the transverse 
section of the proboscis of the mole, PI. 14, fig. 1). 
In Echidna there is no m. maxillo-labialis, a lack which may 
be the consequence of the slight mobility of the snout. 
4. BUCCINATOR-GROUP. 
The muscles, which we unite under this head, form the bulk 
of the cheek and the lips. 
In Echidna (PI. 10, fig. 1) the group is represented by the 
buccinator muscle alone, whose fibres have a transverse (dorso- 
ventrad) direction, going from the upper to the lower jaw; the 
foremost fibres are bent, the convexitj r to the rear, the upper 
and lower ends thereof being directed into the lips, which are, 
as is well known, very feebly developed in Echidna. 
From a buccinator similar to that of Echidna the more com¬ 
plicated conditions found in other Mammals may probably be 
derived. The starting point is as follows (comp. PI. 17, fig. 3): in 
the cheek there is found a layer of transverse fibres somewhat 
bent, the convexity caudad; the ends of these fibres are connected 
with the upper and lower jaw; the foremost of them have no 
such connection, but are bent forwards into the upper and the 
lower lip. But in such simplicity the buccinator is not found in 
the Mammals apart from the Monotremata; always there are 
rather considerable complications. 
In Halmaturus (PI. 13, fig. 2—3), at a first glance, the condi¬ 
tions appear to be of a primitive character, but on closer inspec¬ 
tion we find that here already are complications. The superficial 
fibres of the buccinator are rather well adapted to the scheme, 
being transverse; and also deeper lying bundles have the same 
or a similar direction; but still deeper, near the mucous mem¬ 
brane, there are fibres going at right angles to the others, having 
thus a more longitudinal dii’ection. Near the anterior end of the 
muscle the anterior ends of the maxillo-labialis and platysma are 
inserted into it. The fibres of the buccinator lying outside the 
ends of the said muscles are those, which ai’e bent into the up¬ 
per and the lower lip; we tei’m them pars rimana buccinatorii. 
In the upper lip there is still a vei'y large part of buccinator- 
fibres lying inside the pars rimana; these fibres have another 
direction, viz. transverse (dorso-venti'ad): pars supralabialis bucci¬ 
natorii (PI. 13, fig. 3). — The ends of the buccinatoi'-fibres ai’e on 
some places inflected, following the mucous membrane and being 
inserted on the jaws near the teeth; this is the case with the 
l ) In Myogale moschata the muscle agrees almost exactly with that of Talpa; 
it takes its origin in the same place (above and a little behind the ear), has the 
same relation to the other muscles and is composed of live small muscular bellies, 
which all behave as in Talpa. 
hind part of the supi’alabialis-bundles and with most of the 
bundles of the cheek-portion of the buccinator; but other fibres, 
viz. the front part of the supralabialis and the upper ends of 
the fi’ont part of the cheek-portion, have a simple dorso-ventrad 
direction, being inserted on the jaw farther above.—Within the 
pai’s supralabialis lies the musculus nasalis (PL 13, fig. 3). It is a flat 
muscle, which takes its origin from the intermaxillary bone, near 
the teeth, and passes close to the bone upward; it is somewhat 
expanded at the top, the fibres ending in the skin. In an ana¬ 
logous manner, on the lower jaw, below the incisors, arises the 
m. mentalis (PI. 13, fig. 3), which also lies close to the bone; from 
their origin the fibres pass downwards, and somewhat backwards, 
and terminate in the skin of the lower jaw. Whether these two 
muscles are differentiated parts of the buccinator or not we ai’e 
not able to decide. But we think it probable that they are. 
As we have mentioned above, in Halmaturus some of the 
deeper fibres of the buccinator have taken another, more longi¬ 
tudinal direction than the rest, which have a transvei’se direction; 
a distinct stratification of the muscle has not yet been evolved. 
In the Ungulata (PI. 16) which we have examined this has gone 
further, the muscle being universally divided in two, distinct 
layers, the superficial one of which consists of fibres which have 
mainly a transverse direction, while the deeper la 3 r er generally 
has a longitudinal direction; both layei’s are generally in some 
places, especially at the hind end, intimately connected. The 
fibi’es of the transverse layer may be partially interrupted in the 
middle by a longitudinal inscriptio tendinea (Hoi’se, PI. 8, fig. 1). 
Sometimes thei’e may be a third, and deepest layer, partly trans- 
vei'se, partly longitudinal (Zebu, Tapir, PI. 16, fig. 11, Horse, PI. 16, 
fig. 14). Further we note, that from the ventral border of the 
buccinator some longitudinal, superficial bundles have to a cer¬ 
tain degree separated from the rest of the muscle and taken a 
direction into the median pai'ts of the lower lip: m. depressor labii 
inferiors (PL 16, fig. 3, 5, 7,12,15). The pars rimana is as in Halma¬ 
turus a continuation of the ti’ansverse buecinatorius-layer; but some¬ 
times also the deep, longitudinal layer concurs into the formation 
of it (Wapiti, Zebu and others). Sometimes (Horse) the pars ri¬ 
mana forms a real sphinctei', in others the anterior ends of the 
bundles end in a fibrous median portion of the lips. Thei’e is 
generally a well-developed pars supralabialis (PL 16, fig. 2, 4, 6 etc.; 
PL 6), consisting as in Halmaturus of transverse fibres; it appears 
generally as a continuation of the longitudinal buccinatorius-layer, 
whose bundles take a different direction in the upper lip; in Sus 
it is reduced. — The m. nasalis is in the Ungulata rather strongly 
developed, being in most Artiodaclyla (PL 11, fig. 1 and 5) divided 
into several layers, which take their origin successively from the 
lower margin of the intermaxillary bone and further above (and 
sometimes also from the soft nasal wall or from the nasal carti¬ 
lage); the layers are partly separated by the tendons of the 
maxillo-labialis. — Also the m. mentalis (PL 5, 6) is well deve¬ 
loped, and may, in the Artiodactyla, be divided into layers as 
the m. nasalis; in others it may radiate diffusely into the skin. 
As a further instance we may take the buccinator of the 
Dog (PL 16, fig. 17). The cheek-portion of the muscle is short, 
the mouth-cleft going far back. The superficial layer consists of 
fibres, which are all bent into the upper and the lower lip, the 
part of the muscle lying in the upper lip being far stronger than 
that in the lower lip; the posterior bundles are interrupted in 
the middle by a sort of tendinous raphe. The anterior end of 
the infralahial part is inserted on the lower jaw. In the deeper, 
longitudinal laj'er the fibres are all posteriorly longitudinal, but 
the front end of the dorsal fibres are inflected and inserted into 
the above mentioned raphe, while the more ventral fibres are 
going to the angle of the mouth. A pars supralabialis is not 
present. — Musculus nasalis and mentalis are present. 
In Erinaceus (PL 16, fig. 18) the superficial layer of the bucci¬ 
nator behaves in nearly the same manner as in the Dog. The 
deeper, longitudinal layer is all longitudinal; the ventral parts 
thereof are rather strong and extend into the lower lip. The m. na¬ 
salis (PL 11, fig. 3) is split in several layers between which the. ten¬ 
dons of the maxillo-labialis are situated. The m. mentalis is present. 
2 * 
