ANATOMY OF BALA2N OPTEEA EOSTEATA. 
239 
which was exposed by raising off the dark-coloured integument and subjacent fascia; it 
consisted of a fan-shaped series of converging fibres, which arose from the outer border 
of the superior maxillary bone as far forwards as the anterior extremity of the intermax- 
illary and the tip of the cartilaginous septum or primordial vomer, extending backwards to 
the anterior extremity of the malar bone, and to that portion of the superior maxilla 
which formed the front wall of the temporal fossa. It was also connected with the 
dense fascia investing its superficial surface ; the fibres of the muscle passed inwards, 
converging, and were inserted, the most anterior, into the cartilaginous median raphe 
that extended from the extreme point of the snout to the anterior extremity of the me- 
dian sulcus or groove interposed between the lips of the external nares. The middle 
and posterior fibres ran to be inserted into the outer lip of the nares by a flat expanded 
tendon. From the direction of the fibres of this muscle its use appeared to be to diva- 
ricate the alee or lips of the nares, and by so doing to give free access to the air either 
during inspiration or expiration. 
The second or middle plane of muscular fibres consisted of two parts ; first, a frontal 
portion, retractor alee nasi, which was probably a representative of the pyramidalis 
nasi ; it arose fleshy from the depression on the anterior and external portion of the 
frontal bone immediately in front of the anterior occipital crest ; the fibres of this portion 
ran directly forwards, forming a fleshy belly about 3-| inches in length, which was 
inserted into the cartilaginous part that formed the posterior and lateral part of the lip 
or boundary of the nares. The use of this portion of the muscle appeared to be to re- 
tract and fix the posterior and external lips of the nares, and in conjunction with the 
following muscle to close these orifices. The second portion of this muscle, or con- 
strictor naris, arose from the anterior edge of the temporal fossa, and from the upper 
edge of the superior maxillary bone ; its fibres passed, in a curved direction, forwards and 
inwards to be inserted into the anterior superior surface of the median cartilaginous 
raphe, some of the fibres passing into the outer lip of the nares, and others into the 
upper edge of the superior maxilla. The fibres of this muscle in passing forwards took 
an arched course, the concavity of which was directed inwards and upwards, and 
with the corresponding muscle on the opposite side embraced the nasal outlets like a 
sphincter; consequently, when these muscles contracted simultaneously, their action would 
be to compress the external alee of these outlets and so close the nasal apertures. These 
muscles are probably the homologues of the compressors nasi. 
The third, or deepest plane, was formed of a single muscle on each side, which arose 
from the whole of the upper and inner surfaces of the intermaxillary bone, and from the 
inferior and external aspect of the cartilaginous mass or primordial vomer, which occu- 
pied the fossa between these bones ; the fibres curved outwards and backwards, and were 
inserted into the side of the cartilaginous body forming the outer boundary of the naris. 
This muscle, probably the representative of the depressor alee nasi, seemed available to 
open the nostril, its action being to rotate the alar cartilage, and thus to withdraw these 
moveable nasal pads. 
