17 
Mammals generally. 
Ear-muscles in Placentals with a scutellum. 
18 
As to details of the m. scutularis we note the following. In 
the Dog (PL 15, fig. 5) — where the muscle is stronglj' developed 
and extends far forward on the front — as well as in the Rabbit 
and the Elk the hindmost dorsal part of the m. scutularis joins the 
corresponding one of the other side across the head and forms a 
great muscular plate going from one scutellum to the other. In 
Swine an aponeurosis unites the dorsal ends of the scutularis-fibres 
of the right and left side. In the Dog the foremost ventral part, 
pars antero-ventralis nob. (PI. 12; PI. 15, fig. 5), of the scutularis 
has a certain similarity to the pars zygomatica platysmatis of 
many Mammals and has indeed received the name: m. zygoma- 
ticus; it is a narrow oblique ribbon extending from the scutel¬ 
lum into the upper lip; in the other forms with a scutellum 
examined by us this part of the muscle is not developed in this 
manner, and the whole ventral part does not extend far down 
on the face. The scutularis of the Tapir (PI. 7) is peculiar in 
that a small anterior portion, taking its origin from the skull 
above the eye, is connected through a rather long tendinous 
band with the rest of the muscle, which otherwise does not ex¬ 
tend so far in front. 
As mentioned above the pars transiens musculi scutularis is 
composed of fibres of the scutularis crossing the scutellum and 
of others arising from it. If we imagine, that the crossing 
fibres of the pars transiens disappear, those of its fibres, which 
take their origin from the surface of the scutellum would alone 
be left, and the pars transiens would then appear as a separate 
muscle arising from the scutellum. In Swine, at least in the 
specimen figured (PI. 9), this emancipation has for the most part 
taken place, the dorsal bundles of the pars transiens being all 
quite separate. 
We make this remark because there arises from the scutellum 
two muscles, which we think may possibly have been developed 
from the scutularis in this manner and which therefore we rank 
with the scutularis-complex. One of these is the m. levator brevis 
(»kurzer Heber«) of the Veterinarians (PI. 15, fig. 4), which arises 
from the outer surface of the scutellum and is inserted into the 
convex surface of the ear (Horse, Tapir, Elk, Cow; in the other 
forms examined we have not found this muscle). As to the 
derivation of this muscle from the scutularis comp, the description 
of the scutularis of Didelphys given below. The other muscle, 
which we are inclined to derive from the scutularis, is the m. ro¬ 
tator (PI. 15, fig. 5), a strong muscle arising from the inner surface 
of the scutellum; its fibres are directed backward (and down¬ 
ward) and inserted into the proximal part of the mediad side 
of the auricle; in the Horse and Tapir it consists of two distinct 
crossing portions 1 ). 
b. Auriculo-occipitalis-group. 
PI. 15, fig. 4—6. 
The m. auriculo-occipitalis is a lamelliform muscle taking its 
origin on the occiput and the neck from a tendinous median 
dorsal line, where it meets the corresponding muscle of the other 
side; it extends over the pinna, into whose mediad side it is in¬ 
serted; in addition it is inserted into the scutellum, and the fore¬ 
most part of it frequently extends as a muscular plate on the 
dorsal side of the head. It has its place behind the scutularis; as 
far as it extends into the same region as this, it is covered by the 
scutularis. The direction of the fibres of the auriculo-occipitalis is 
posteriorly chiefly transverse, anteriorly longitudinal. The anterior 
part, consisting of longitudinal fibres and extending on the dorsal 
side of the cranium, we term the epicranial part; the next part, in¬ 
serted into the scutellum, we term the scutellular part, the last 
part, inserted into the auricle, the auricular part. They may be 
confluent or more or less separated. The epicranial part may 
be wanting. 
In the Dog (PI. 15, fig. 5) the muscle is fully developed: it ex¬ 
tends on the auricle, is further inserted into the scutellum and 
extends forwards on the dorsal side of the head (the lastnamed part 
9 In the Cow, where the muscle has a more dorso-ventrad direction than usual, 
a rather large foremost part of it inserts partially into the deeper portion of the m. 
postauricularis, partially into a prominence of the skull above the bony meatus. 
of the muscle is the in. epicranius s. occipitalis of Ellenberger-Baum, 
Anatomie des Hundes). In a similar manner the muscle is deve¬ 
loped in the Rabbit, the Lama and the Elk: the muscle is inserted 
into the auricle (in the Elk through a separate slip) and further 
into the scutellum, and it is continued on the upper side of the 
head. In the Swine examined the muscle is rather small; it is deeply 
split up into five slips, of which the four first have all the same 
direction: obliquely-forward; the hindmost of these four inserts 
partially into the scutellum, the rest is epicranial. The fifth slip in¬ 
serts into the ear. In the Tapir (PI. 7) the muscle is separated into 
three portions, the hindmost inserting into the auricle; the two an¬ 
terior extend both beneath the scutularis, none of them reaching 
the scutellum. In the Horse the epicranial part has disappeared, but 
the auricular and scutellular are both well developed and only 
partially separated; the scutellular part, which is a broad plate 
largely tendinous, is generally described as a deep layer of the 
m. scutularis. In the Cow the epicranial part has also disappeared 
and the auricular and scutellular parts are intimately connected. 
Inside the auriculo-occipitalis, from the same tendinous line 
on the occiput and the neck, the musculus postauricularis (= m. 
auricularis posterior of Ruge) takes its origin (PI. 15, fig. 5). It con¬ 
sists firstly (1) of a superficial part, which is inserted into a line 
on the caudad side of the auricle; it is in the Swine a broad 
fanshaped continuous muscular plate, but generally is split up 
into two (Horse, Tapir, Cow, Rabbit) or three (Elk, Dog) digitiform 
portions (PI. 15, fig. 6), which at their origin generally cohere, but 
more or less widely separated run to the auricle; of the three 
digitations in the Dog the foremost is inserted into the scutellum, 
but in the Elk all are inserted into the auricle (from the fore¬ 
most digitation in the Elk some fibres insert also into the scu¬ 
tellum) 1 ). Secondly (2) there is a deeper part, which arises poste¬ 
riorly either separately from the above-named tendinous line (Dog, 
PI. 15, fig. 5; Rabbit) or from the inner side of the superficial part 
(Ungulata generally) or from both 2 ) (Elk, PI. 15, fig'. 6); it inserts 
below the insertion of the m. rotator hard above the incisura 3 4 ) 
2 + 3. — As to the original connection of the postauricularis 
and the auriculo-occipitalis comp, the statements below on the 
Marsupials. 
To the auriculo-occipitalis-group further belong the muscles 
which in the veterinary anatomical treatises are termed : mm. ad¬ 
ductor medius and inferior. 
The m. adductor medius is, in the Swine (PL 9), quite a separate 
muscle taking its origin from the inferior margin of the scutellum 
and inserting into the anterior side of the auricle covered by the 
pars transiens musculi scutularis. Also in the Tapir it is quite a 
separate muscle. But generally in the animals examined it ap¬ 
pears partially as a continuation of the auriculo-occipitalis, some 
of the fibres taking their origin from the scutellum but others 
being a continuation of fibres of the auriculo-occipitalis. Such is 
the case in the Rabbit, the Horse, the Cow and the Elk. In the Dog 
(PL 15, fig. 5) the foremost slip of the m. postauricularis is inside 
the scutellum confluent with the auriculo-occipitalis and from this 
muscle part of the fibres of the adductor medius arise, while 
others arise from the scutellum' 1 ). 
While, from a comparison of the animals in question we 
might contend that the adductor medius is a portion of the auri¬ 
culo-occipitalis, this is not possible with regard to the adductor 
inferior, which is in all these forms quite a separate muscle; it 
is only by taking the Marsupials into comparison that it may 
be demonstrated, that this muscle also is part of the auriculo- 
occipitalis (comp, below p. 21). 
The m. adductor inferior (PL 15, fig. 4) is a fanshaped flat 
muscle, which takes its origin from the lower margin of the scu¬ 
tellum and from the face below it (sometimes from the zygoma) 
and inserts round the incisura posterior 4 near the insertion of 
*) The foremost of the two muscular slips in the Horse has a more eaudail direc¬ 
tion than general and inserts into the auricle with a narrow tendon, not broadly as 
usual; it gives rather the impression of a separate muscle (»mitllerer Heber«, levalor 
medius, of the Veterinarians). 
2 ) Also in the Dog there is a connection between the superficial and the deep 
part of the m. postauricularis (Pi. 15, tig. 5). 
3 ) Comp, as to »incisura«, »anteron« and »posteron«, Boas, Z. vergl. Anat. d. 
Ohrknorpels der Saugetiere, in. Anat. Anzeiger 30. Bd., 1907, p. 434—42. 
4 ) In the Dog there is a separate muscular slip, which inserts into the anteron 5 at 
the inner angle of incisura 4, and which sometimes appears as a direct continuation 
of the postauricularis; this little slip is not present in the other animals examined. 
3 
