Linnean Society, 129 



a particular account of his dissection of an adult female, which at the 

 time of death was suckUng a young one nearly half-grown. In this the 

 panniculus camosus which covers the anterior surface of the belly was 

 of extraordinary thickness, and composed principally of perpendicular 

 muscular fibres, which in their course from the thorax downwards sur- 

 round the mouth of the pouch to which they form a sphincter muscle, 

 and a fasciculus of its fibres descending over the symphysis pubis is 

 inserted into the sphincter muscle of the cloaca ; so that the contraction 

 of this part of the panniculus carnosus would operate powerfully in ap- 

 proximating the external aperture of the vagina with the mouth of the 

 pouch. 



On removing the panniculus carnosus a pair of muscles (of which 

 the attachments and uses have been hitherto incorrectly described) are 

 brought into view. Each of these muscles is of a triangular shape, 

 being attached by a narrow origin to the posterior part of the pelvis ; 

 and expanding in its course is continued transversely round the lower part 

 of the belly, before the abdominal muscles, and immediately above the 

 brim of the pelvis. Each of these triangular muscles encloses, between 

 an anterior and a posterior layer of its fibres, the mammary gland, and 

 the two muscles afterwards cross the fore part of the abdomen to unite 

 in front of the linea alba. By this union a perfect muscular girdle is 

 formed, by the contraction of which the mammae are compressed against 

 that part of the abdominal parietes in which the marsupial bones lie im- 

 bedded. 



May 4. — The reading of Mr. Morgan's paper was continued, con- 

 taining further particulars of the dissection of the mammary organs of the 

 adult and impregnated Kanguroo, as well as of the muscles attached to the 

 marsupial bones. These bones, with their ligamentous and muscular 

 connexions, were described, and several errors in Sir E. Home's pub- 

 lished accounts of these parts were pointed out. The authour then 

 stated his own opinions respecting the use of these structures. He stated 

 that the marsupial bones are formed: 1st., for the purpose of giving that 

 firm support to the superincumbent abdominal viscera, which the narrow 

 pelvis of the animal is incapable of affording while in the erect posture ; 

 and 2ndly., for the purpose of constituting a fixed point of resistance, 

 against which the mammae are squeezed by the muscular girdle already 



