21 
Mammals generally. 
Ear-muscles of Marsupials. Do. in Plaeentals without scut. Monotremes. 
22 
direction; the foremost portion is the largest, the hindmost the 
smallest. We term them pars anterior, intermedia and posterior. 
The pars anterior and intermedia represent together the m. auri- 
culo-occipitalis of the Plaeentals. The pars anterior is fanshaped, 
the muscle taking its origin from the posterior end of the sagittal 
crest, from which point the fibres diverge, those near the median 
line having a longitudinal direction, while those of the lateral 
parts have a direction somewhat transverse. In front of the 
opening of the ear-conch (fig. A) is situated a narrow muscular 
slip, which is inserted into the posteron 4 near the insertion of 
the auricular portion of the sphincter profundus; it evidently 
corresponds to the adductor inferior of the Plaeentals. If we fol¬ 
low the fibres of this muscular slip from their insertion we find 
them going dorsad, below the terminal part of the scutularis, and 
being continued into some of the above-named lateral fibres of 
the anterior part of the muse, auriculo-occipitalis, while others 
are inserted direct on the auricle (anteron 5). Where the fibres 
of the two muscles, the scutularis and the auriculo-occipitalis, 
cross one another, they are intimately connected. It is evidently 
in this place that the scutellum has been developed in the Pla- 
centals; and as a consequence of the development of the scutel¬ 
lum parts of the two great muscles have been cut off respectively 
to form the levator brevis (from the scutularis) and the adductor 
inferior (from the auriculo-occipitalis). — The pars intermedia is 
inserted into the convex surface of the auricle much as the 
posterior part of the auriculo-occipitalis is inserted in the Pla- 
centals. — The pars posterior of the muscle inserts into the au¬ 
ricle in the same place as the deep portion of the postauricularis 
of the Plaeentals and evidently corresponds to this. In what 
manner the superficial portion of the postauricularis in the Pla- 
centals has taken its origin we cannot say with certainty. In 
Didelphys there is no trace of it. Possibly it has arisen from 
the pars intermedia of the auriculo-occipitalis + postauricularis of 
Didelphys, this portion having been split up into two layers, of 
which the deeper has been developed into the superficial portion 
of the postauricularis. 
In Halmaturus the m. scutularis and the auriculo-occipilalis 
+ postauricularis behave in the main in the same way as in Di¬ 
delphys, but the anterior part of the auriculo-occipitalis + posl- 
auricularis has a somewhat more complicated structure. 
The m. temporo-auricularis is in Didelphys quite similar to 
that of the Plaeentals and gives no key to the understanding of 
this muscle. It takes its origin from the mandible, and is in¬ 
serted into the anteron 5 and the neighbouring parts of the au¬ 
ricle, below the insertion of the scutularis. — In Halmaturus (PI. 13, 
fig. 3) this muscle differs in taking its origin from the hind part 
of the zygoma (comp, the Plaeentals). 
The muscles, which both arise from, and are inserted into, 
the auricular cartilage, we have only studied in Halmaturus; which 
possesses the same muscles as the Dog. They present no marked 
features of interest. 
The m. anteri sexti (PI. 13, fig. 2; comp. fig. 3) has its place 
before the anteron 6, bridging the incisure which separates a 
proximal spiniform part from the rest of the anteron. 
The m. posteri septimi (PI. 13, fig. 1—2; comp. fig. 3) is a flat 
muscular band going from the proximal margin of the posteron 7 
to the posteron 5 bridging the broad incisure between them. 
The m. fissuralis takes its origin from the concave (hinder) 
side of the anteron 5, and is inserted into the end of the poste¬ 
ron 4. 
The m. trago-anterus arises from the proximal corner of the 
anteron 5 and is inserted into the posteron 4 outside the m. fis¬ 
suralis. 
C. The ear-muscles in Plaeentals 
without a scutellum. 
Among the Plaeentals, in which no scutellum is developed, 
we have studied the ear-muscles of Cenietes (fig. B, C). We only 
describe the muscles going from the head to the auricle. 
Of greater ear-muscles Centetes possesses the same as other 
Plaeentals, viz. scutularis, auriculo-occipitalis and postauricularis. 
Besides these there is an adductor inferior and a temporo-auri¬ 
cularis. 
The scutularis (fig. C) is divided into three portions, which 
appear as separate muscles, 1) an antero-superior, 2) an antero¬ 
inferior and 3) a posterior portion. The first (a) arises on the up¬ 
per side of the skull in front of the eye, close to that of the 
opposite side; only the inferior fibres thereof reach the ear (an¬ 
teron 5), the superior ending free, intermingling with those of 
the other portions. The second portion (c) takes its origin from 
the angle of the mouth (comp, the pars antero-ventralis of the 
Dog, p. 17) and goes to the ear, where some bundles of it insert 
into the anteron 5, while the rest extend above the ear, the 
fibres intermingling with those of the fust and the third por¬ 
tion ( b ) which latter has a transverse direction and, in the middle 
line, joins the corresponding muscle of the other side, thus for¬ 
ming a broad muscular band going across the skull from one 
ear to the other; only the posterior bundles, corresponding to 
the pars transiens, reach the auricle, the rest intermingle with 
the fibres of the two other portions. 
Close in front of the antero-inferior portion (c) is situated a 
muscle (d) taking its origin from the small zygoma below the 
eye, and ending, halfway between the eye and the ear. We sup¬ 
pose that this muscle is a detacted part of the antero-inferior 
portion of the scutularis. 
The auriculo-occipitalis (fig. C) is a large, thin, muscular plate 
which takes its origin from a long tendinous stripe on the oc¬ 
ciput and the neck and only at its antero-external angle is in¬ 
serted into the auricle, while for the rest, it covers the dorsal 
side of the head between the auricles, and further forward. 
The postauricularis (fig. C) consists of a superficial part com¬ 
posed of two deeply separated slips, and of a deep portion, 
represented by a long slender muscular ribbon. 
The adductor inferior (fig. B) arises on the face, in front of 
the ear, and extends backward inserting into the base of the. 
tragus. 
The iemporo-aiiricularis takes its origin from the mandible 
and is inserted into the anteron 5. 
Of the ear-muscles of Centetes the scutularis is of special 
interest. We suppose, that Centetes is to be derived from a Mam¬ 
mal which possessed a scutellum, in other words, that the ab¬ 
sence of this has not as in the Marsupials a primitive character. 
The several portions into which the scutularis is separated we 
think is an indication of the original presence of a scutellum, 
lying in the place where the greater part of the fibres of the 
three portions meet one another. The connection of the scutularis 
with the auricle we regard as secondary (that of the pars trans¬ 
iens naturally excepted). 
In a similar manner we think that the ear-muscles of other 
Plaeentals lacking a scutellum should be interpreted. But we 
have not been able to spare time for making further investigations. 
D. The ear-muscles of the 
Monotremata. 
We regret to say, that the Monotremata, of which we have 
examined Echidna (PI. 10), do not afford decisive contributions 
to the understanding of the ear-muscles. 
The rather large ear-cartilage of Echidna is almost wholly 
imbedded in the large muscular mass of the plalysma. An inser¬ 
tion into the auricle takes place only to a very limited extent. 
On the mediad side there is inserted a well-defined bundle of 
the platysma. This having a dorso-ventrad direction, perhaps, is 
the homologue of the terminal slip of the scutularis in Didelphys. 
Another slip, having a direction from behind forward, is inserted 
into the hinder side of the tragus, into which is also inserted a 
small portion of platysma taking its origin from the anterior 
margin and the adjoining part of the concave side of the au¬ 
ricle ( b, PI. 10, fig. 1); and of the platysma-bundles which go to 
the angle of the mouth the deeper ones take their origin from 
the tragus; whereas the superficial ones come from the bulk of 
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