DE. J. MUEIE OX THE FOEM AND STEUCTUEE OF THE MANATEE. 139 



The posterior common ligament within the spinal canal was not examined. 



I observed in nine or ten of the anterior dorsal vertebrae an extra ligament. This 

 passes as a more or less strongish band from the posterior surface or border of the 

 lower portion of the vertebral lamina to the anterior border of the transverse process, 

 and over the articulating process. From the fourth to the seventh vertebra it is well 

 marked, but is less distinct in the succeeding ones. 



The capsular ligament is divided by a strong interarticular spur from the inter- 

 vertebral. The two synovial cavities are very distinctly separate. 



Of the true ligamentous bands lashing the costse to the spinal elements, each stellate 

 ligament is only imperfectly divided into two bundles. 



The anterior costo-transverse ligaments of human anatomists are wanting. 



But in all the ribs there are developed short, but immensely strong, middle costo- 

 transverse ligaments. These are situated deeply, and pass in an oblique direction 

 between the ribs and the transverse processes. They are covered by a portion of the 

 external intercostal muscles, and partly surrounded by the intervertebral plexus of 

 vessels. 



Every one of the eighteen posterior costo-transverse ligaments is remarkably broad 

 and strong. Along with the stellate ligament the middle costo-transverse ligament 

 prevents the rib rotating too far forwards. 



3. Limbs, Pelvis, and Ligaments. 



Vrolik's portraiture (pi. 3) and remarks (/. c. p. 69) on the progressive development 

 of the pectoral limb are sufficient for practical purposes. In his larger specimen the 

 ossific centres of the phalanges, three to each and two to the thumb, are not quite so 

 rigidly defined as in that coming under my own observation. The ligaments connecting 

 the limb-segments are very simple, the flattened condition of the bones obviating much 

 differentiation ; and each joint is uncommonly lax. The tendon of the subscapularis 

 pierces and greatly strengthens the shoulder-joint. 



The pelvic bones of two males at different ages have been delineated in the ' Bijdragen ' 

 (pi. 5) ; and, excepting in greater circularity of the central mass, my young male agreed. 

 In the older female ossification had proceeded further. The figure of the bone is 

 furcate or semilunar, therefore differing from the adult male, where it has an irregular 

 diamond-shape. The extremities of the horns are cartilaginous, the rectus abdominis 

 muscle being inserted between {vide fig. 50) ; and the posterior concave border has 

 likewise a cartilaginous rim, to which the ischio-coccygeus is affixed. On the inner 

 border the transversus periusei &c. are attached. This edge, therefore, represents the 

 ischium, the tuberosity being that turned rearwards ; the anterior cartilages tipping 

 the cornua are respectively pubis and ilium. The surfaces of the bone are smooth, 

 and indeed slightly concave ; but all limb-structure is absent. The relative dimensions 

 of the pelvis were :— male, i inch in diameter; female, about l^ inch in long and 1 inch 



