20 FISCHER ON THE PELVIS OF THE MAMMALIA. 



row. The middle vertebrae are the longest, especially 7 of them ; in the lion 

 the length of the longest vertebra is 2", 2'", in the leopard I' 1 , 2"', in the 

 didelphis opossum 10'", in the common weasel (mustela vulgaris) 2"'. The 

 mustela vulgaris has abdominal spinous processes, like those of the rat, but 

 the mustela putorius has short broad abdominal spinous processes between 

 the first caudal vertebrae ; these processes have the summit bifid. The hedge- 

 hog seems rather to have sesamoid bones at the joints of the coccygeal verte- 

 brae, than true abdominal spinous processes. Autewreith. 



Section 21. Ossa innominata. As the length and proportions of these 

 bones, whether compared with each other or with the other bones of the pelvis, 

 may be best seen by inspecting the table of dimensions at the end of the dis- 

 sertation, I shall here only speak of what seems most worthy of notice. The 

 pelvis of the genus didelphis, in addition to the usual number of bones, has 

 two which all other animals want. The didelphis, as is well known, has a 

 pouch in the lower part of the abdomen, in which the young live after they are 

 born until they have attained a fitting age. This pouch is supported by two 

 bones, which may be called its janitors. EdwardTysonf has left us an excellent 

 description of these bones of the pelvis in the opossum. " These marsupal 

 bones, or janitores marsupii, are two strong bones, in length about two 

 inches, and so united to the superior and inferior margins of the bones of the 

 pubis, that at their base, where they unite with the bones of the pubis, they 

 touch each other, whilst at their other extremity they are distant from each 

 other by about two and a half inches. At the basis, two heads may be seen, 

 about half an inch broad ; the larger one turned towards the symphysis of the 

 os pubis, the other, the smaller one, towards the haunch bone, together with 

 an intermediate sinus between these heads, in which is received a certain pro- 

 tuberance of the os pubis. (In the didelphis, the protuberance of the os pubis 

 does not correspond to the marsupial sinus, but a certain obtuse notch of 

 the margin of the os pubis corresponds to it. AutenreitJi.) These bones, 

 which as they ascend from the bones of the pubis become more slender, and 

 about the middle do not exceed a quarter of an inch in length, cannot be 

 moved towards each other, nor from each other, but inwards, as it were towards 

 the spine, and outwards from it." Whilst, however, they are moved outwards, 

 they are of necessity widened, whilst inwards they are closed, because their 

 bases by turns form an angle. The bones of the pubis and of the ischium are 

 very large and long in the gigantic didelphis ; the os ischium is likewise as long 

 as the os ilium. The rami of the os pubis and ischium are so united that no 

 angle exists between the branches of the os ischium in the inferior aperture of 

 the pelvis. The foramina ovalia are very long, and the acetabulum placed in 

 the middle length of the pelvis has no notch. The ossa pubis of the European 

 mole are separated from each other ; in the shrew the distance is three lines. 

 BlumenbachJ says" Unter den vierfiissigen saugthieren hat der Maulwurf 

 wol eins der sonderbarsten Beken. Es ist so eng und schmal, dass es ausser 

 einigen schlanken Muskeln, bios Kerven und Blutgefasse zu fassen, im stande 



t Mich. Bernh. Valentin! amphitheatrum Zootomicum. Giesse 1720, fol. p. 132, et deli- 

 neatio horum ossium in Tab. xxvi., Fig. 5. Praestantissimam delineationem pelvis didelphidis 

 giganteae dedit E. Home, in commentatione sua: Observations on the mode of generation of 

 the Kangaroo in Philosophical Transactions, 1795 ; 4 Tab., xxi. 



* T. F. Blumenbach, Geschichte und Beschreibung der Knochen, p. 328. 



