28 



DR. r. O. PARSONS ON THE [Jail. 15, 



Tnmh-Musdes. 



Panniculus camosm.— This is very specialized, probably in con- 

 nection with the undergroimd habits of the animal, so that the 

 typical mammalian dorso- and abdomino-humeralis muscles are 

 remarkable for their absence, and their characteristic relation to the 

 pectoral muscles is wanting. As usual, there are many layers of 

 fibres in the panniculus, and to many of these special names have 

 been given by Dobson. The main scheme consists of a longitudinal 

 set of fibres running over the back region from the root of the 

 snout to the root of the tail, forming Dobson's occipito-frontalis 

 and dorso-cuticularis, while various oblique bands cross the general 

 antero-posterior direction of the fibres and acquire attachments 

 to fixed points, such as the acromion process, the elongated 

 auditory meatus, and the ligamentum nuchee. In this way the 

 acromio-cutic-ularis, occipito-cuticularis, dorso-cuticularis, cervico- 

 cuticularis, cervico-auricalaris, and retractor naris are formed ; 

 muscles which in our specimen fully bore out Dobson's descriptions 

 of them (test-fig. 0, p. 27). 



The ventral panniculus consists of the platysma in the neck and 

 a set of abdominal fibres which have the same direction as those 

 of the external oblique ; some of these fibres are prolonged down 

 over the anterior (cephalic) surface of the leg as far as the 

 dorsum of the foot. There is, so far as I could see, no indication 

 of the sterno-facialis or sphincter colli so common among mammals ; 

 but a muscle runs almost directly outward from the manubrium 

 sterni on a deeper plane than the ventral panniculus with which 

 it ultimately blends, and is well-named by Dobsou the sterno- 

 cuticularis. The specimen in my possession shows that this muscle 

 lies superficial to and probably compresses the anterior of the 

 two mammary glands. The ]wsterior mammary gland lies in the 

 groin and extends as far as the front of the knee, it is merely 

 covered by the general fibres of the ventral panniculus. 



The muscles of the head, neck, and trunk closely correspond 

 •with Dobson's descriptions ; perhaps the following points, however, 

 may be worth calling attention to. There are three separate parts 

 to the sterno-cleido-mastoid :— 1. The sterno-mastoid is inserted 

 separately by tendon. 2. The cleido-mastoid is inserted by flesh. 

 3. The cleido-occipital which near the clavicle lies superficial to the 

 last, and is separated from it by the spinal accessory nerve. 



The two parts of the trapezius are widely separate as in Dobson's 

 specimens ; the anterior portion only is inserted into the acromion. 

 Both parts are supplied by the spinal accessory nerve. 



The hinder (caudal) part of the rhomboids passes across the 

 mid-dorsal line to join its fellow of the opposite side. This 

 arrangement is described by Dobson as the transversus scapularum, 

 and reminds one of a similar arrangement of the acromial fibres 

 of the trapezius (acromio-cucuUaris) described by Prof. Windle and 

 myself in certain Carnivores \ 



^ ''■ Myology of Ibe Tei-restrial Carnivora," P. Z. S. 1897, p. 385. 



