15 
Mammals generally. 
Buccinator-group. Lateralis nasi. Recti. Ear-muscles. 
16 
In Lemur the ordinary two layers of the m. buccinatorius 
are developed. The transverse layer is very strong and all its 
fibres are curved into the lips; a great posterior portion of the 
fibres of the upper lip have an oblique direction and are in¬ 
serted into the maxillary bone — as is also the case with part 
of the transverse layer in Halmaturus 1 ). Posteriorly the m. buc- 
cinatorius consists only of the longitudinal layer, extending for¬ 
ward inside the transverse layer, which externally is intimately 
connected with the anterior end of the platysma. 
In the Rabbit (PI. 16, fig. 19) there is in the buccinator a 
superficial, principally transverse layer; but the fibres are partly 
more or less oblique, the most anterior (a) having a direction 
somewhat from above-forward to below-backwards, the next ( b ) 
having in turn a direction from above-backward to below-forward; 
the last named crossing and overlaying the former. Inside this 
transverse layer there is a well-defined longitudinal layer ex¬ 
tending also into the upper lip. On the side of the maxilla, 
dorsad to the parts described of the buccinator, is situated a 
layer of transverse (vertical) fibres (c), whose ventral ends are in¬ 
serted into the buccinator; this muscular plate is evidently a se¬ 
parate part of the buccinator (comp, the buccinator of Halma¬ 
turus, where also part of the muscle extends upon the upper jaw). 
In Myopotamus (PL 14, fig. 4) the ends of most of the trans¬ 
verse buccinator-fibres are not inserted into the upper and lower 
jaw respectively but join the corresponding fibres of the other 
side below the intermaxillary bone, and above the mandible, 
behind the incisors. On the dorsal side, viz. below the intermax¬ 
illary bone, the fibres of the right and the left buccinator pass 
direct into each other. On the ventral side, above the mandible, 
the muscular fibres of the right and left buccinator are very near 
each other, but do not pass direct into one another; the bundles 
passing into fine tendons, which go from one side to the other, 
crossing each other. In this manner a powerful sphincter round 
the front part of the oral cavity is formed. This sphincter is pro¬ 
bably developed in many other Rodents and is the active agent 
in the peculiar shutting of the mouth behind the incisors as is 
the case in manjr Rodents. 
The general results of the foregoing investigation respecting 
the buccinator-group in the Viviparous Mammals may be sum¬ 
marized as follows (comp. PI. 17, fig. 3—4): 
The buccinator-group consists of three muscles: buccinator, 
nasalis and mentalis. The buccinator forms the bulk of the cheek 
and extends into the upper and lower lip. The original trans¬ 
verse arrangement of the bundles, still found in Echidna, has 
been modified so that one may generally distinguish two distinct 
— but in some points intimately connected — layers, a super¬ 
ficial transverse and a deeper longitudinal layer; the anterior 
bundles of the superficial layer are bent so that the ends thereof 
are directed into the upper and lower lip, running parallel to 
the margins of the lips, sometimes joining in front the corre¬ 
sponding portion of the opposite side: pars rimana buccinatorif)-, 
sometimes also the deeper, longitudinal layer takes part in the 
formation of this muscular portion. Within the pars rimana in 
the upper lip is often developed a deeper layer of transverse 
fibres, pars supralabialis buccinatorii, generally appearing as a con¬ 
tinuation of the longitudinal layer of the cheek. Sometimes the 
buccinator presents even other complications: a third, and deepest 
layer may be present; and at the lower margin of the buccinator 
may be developed a special branch of the muscle extending into 
the median part of the lower lip. — The nasalis and mentalis 
take their origin from the upper and lower jaw respectively, near 
the teeth, and extend upward-laterad and downward-laterad, en¬ 
ding in the skin, the first being generally divided into several 
parts separated by the tendons of the maxillo-labialis. We think 
it probable, that these muscles are derivations of the buccinator. 
5. MUSCULUS LATERALIS NASI. 
In some of the Vngulata (Horse, Ruminants with the excep¬ 
tion of the Camels) a muscular fringe consisting of transverse 
!) In the same manner as in the Prosimise also in the Dog and Erinaceus a 
smaller posterior portion of the fibres of the upper lip are inserted into the 
maxillary bone (comp. PI. 16, fig. 17 and 18; the fibres directed obliquely upward). 
2 ) The » orbicularis oris « autt. is partly this muscle, partly the front portion 
of the sphincter profundus (comp. p. 7). 
fibres is present on the border of the soft nasal wall and the 
adjoining bones (nasal, intermaxillary, maxillary) and cartilages, 
the muscular fibres taking their origin from the said bones or 
cartilages and extending on the soft nasal wall. Sometimes it 
may be separated in two disconnected portions. This muscle is 
best developed in the Horse (PI. 8, fig. 1). Also in the Dog (PI. 12) 
we have found traces of it at the posterior end of the lateral 
face of the nasal cartilage. How far it is present in other than 
the said Mammals and the Elephant (vide infra) we are at a loss 
to say; we have not found this feeble muscle in others, but must 
remark that we have not sought much for it, so that it is very 
possible, that it is more often present than would appear to be 
the case. 
From the m. lateralis nasi probably may be derived some 
minor muscles in this region, which run from one part of the 
nasal cartilage to the other or from the cartilage to the soft nasal 
wall. To these muscles, which we have not had an opportunity 
of investigating more closely, belongs the m. transversus nasi of 
the Horse, which is more developed than is generally the case 
with these muscles; some parts of the transversus nasi of the 
Horse are continued direct into the lateralis. 
6. MUSCULI REOTI NASI ET LABIORUM. 
In the lips, and also in the soft parts of the nasal lube, 
there are in manj' Mammals numerous muscular fibres present, 
going transversely from the skin to the mucous membrane. The 
fibres are according to Perregaux 1 ) general^ present in the lips 
and are here termed by Aeby m. rectus labii; in the Ungulata 
which we have examined in this respect they are present. But 
as already stated similar fibres may also be found in the soft 
nasal tube, where we have found them in the Camel, Elk, Horse 
and Tapir and where they have probably a wider distribution. 
We term the lastnamed fibres m. rectus nasi 2 ). 
7. MUSCLES OF THE EXTERNAL EAR. 
The muscles which are connected with the external ear we 
shall treat under this head with the exception of the auricular 
portion of the sphincter profundus, which has already been de¬ 
scribed. Besides the muscles inserted into the external ear or 
being situated wholly on it, we also here treat of those, which 
are inserted into the scutellum, a plate of elastic cartilage situated 
in many Mammals before (and above) the auricle, these muscles 
naturally, as we shall see, ranking among those of the auricle itself. 
A. The ear-muscles in the Plaeentals 
with a scutellum. 
Of Plaeentals possessing a scutellum we have particularly 
examined: Dog, Rabbit, Elk, Cow, Swine, Horse and Tapir. 
a. Scutularis-group. 
PI. 15, fig. 4—5. 
From the middle line of the head, from the hind parts of 
the frontal surface unto above the eye, and sometimes from the 
side of the face behind and below the eye, arises a broad mu¬ 
scular brim, the m. scutularis, inserting into the margin of the 
scutellum, and being divided into several more or less separated 
subdivisions. Often the muscle instead of taking origin from the 
middle line is here continued into the corresponding muscle of 
the opposite side, thus forming a transverse muscular band 
across the head (Dog, PI. 15, fig. 5, Rabbit, Elk). From the 
M. scutularis branches off a bundle, pars transiens 3 ), which is 
not inserted into the scutellum, but crossing it, is inserted into 
the auricle itself (on the convex side near the anterior margin, 
or into this last); some of the fibres of the pars transiens may 
arise from the scutellum. 
x ) Einiges uber die Lippenmuskulatur d. Saugetiere. Inaug. Diss. Bern. 1884. 
2 ) The above-mentioned mm. nasalis and mentalis often join so closely with recti- 
bundles, having also a similar direction, that we may not suppress the remark, that 
it is not precluded, that these muscles, which we have ranked above with the bucci¬ 
nator, are in reality recti-bundles, which have at one end been attached to the bone. 
•) sOberer Einwartszieher«, adductor superior, of the Veterinarians. 
