PELVIS. 



173 



usually contributed to by the pubes and ischia. 

 In Fishes, a supporting arch from the spinal 

 column to the posterior limbs* is not wanted, 

 but rather a free ami unimpeded motion for 

 the caudal extremity, used in propelling the 

 body. 



In the Angler there are two pelvic bones, 

 eacli consisting of a vertical portion, which, in 

 this instance, seems to represent the ilium, and 

 a horizontal one, which meets in a symphysis 

 with the one on the opposite side, and is the 

 homologue of the pubis, the pectoral rays 

 being attached to the angle of union of the 

 two portions. In the Rays and Sharks, 

 where the pelvic extremities are better de- 

 veloped than in other fishes, the pelvic bones 

 consist of one piece, placed transversely, 

 resembling that which supports the pectoral 

 fins, and suspended loosely, like it, by a 

 ligament to the spine. In the Sharks and 

 Chimera are found, articulated to it, by means 

 of an intermediate cartilage, two club-shaped 

 bones, called claspers, which are used to em- 

 brace the female in the generative act. In 

 the Torpedo, and also in the Cyclobatcs oligo- 

 dactylus, an extinct Ray, the pubic bone sends 

 forward two processes, somewhat resembling 

 marsupial bones. In the Sturgeon, the pelvic 

 bones are almost entirely separated from each 

 other, and consist of small triangular pieces, 

 with their apices directed forwards, and sup- 

 porting the cartilaginous fin rays. In the 

 Cod-fish there are two. sub-triangular bifur- 

 cated bones, connected to each other by liga- 

 ment, and suspended from the coracoids, the 

 rays of the ventral fins springing directly from 

 them. In the Trout, the pelvic bones are also 



two in number, flat and of an elongated tri- 

 angular shape, with the base directed pos- 

 teriorly, and supporting the ventral fins (see 

 jig. 111. c). In the Haddock, there is a single 

 bone, presenting a central oval opening with 

 the shorter diameter transverse. In the 

 Cyprinus, Scomber, and Zeus, they present 

 backward spinous projections. In the Rhombus 

 and Loricaria there is seen an ankylosis of 

 the anterior caudal vertebrae, forming a sort of 

 sacrum, and presenting the first indication of 

 the formation of this bone in the animal 

 kingdom. 



Subjoined is a table, showing the compara- 

 tive pelvic angles in Man and the principal 

 genera of Mammalia, Birds, and Reptiles. The 

 measurements were principally taken, with 

 great care to insure correctness, from the 

 specimens in the Hunterian Museum, through 

 the kindness of Professor Owen. The rela- 

 tive size or total disappearance of the verte- 

 bro-'diac, sacro-vertebrc/l, and the ilio-pubic 

 and i/io-ischifil angles in the different tribes, 

 will be here seen at one view. It may be 

 observed that the two former may vary some- 

 what through inaccuracies in articulating the 

 skeleton, or with the variations of the ver- 

 tebral curve, and that the results here given 

 are to be taken in this particular, as approxi- 

 mative only. But the ilio-pubic and.ischial 

 angles cannot, from the ossific union of the 

 bones, be subject to such accidental variations. 



The accompanying diagram is intended to 

 show the absolute lines of direction or axes 

 of the pelvic bones and spine seen in profile, 

 with the angles above referred to, in the prin- 

 cipal pelvic types. 



Fig. 112. 



7\ 



V 



10 



Lines of direction and profile angles of the pelvic bones. 1. Human type; fac, vertebro-iliac angle; fag, 

 sacro-vertebral angle; acd, ilio-ischial angle ; acb, ilio-pubic line, forming an angle in all other animals. 

 2. Orang type. 3. Monkey type, no ilio-ischial angle. 4. Edentata type, ilio-pubic angle reversed. 5. 

 Carnivora type, ilio-ischial angle reversed. 6. Pachyderm type. 7. Kuminant type. 8. Rodent type, 

 no ilio-ischial angle. 0. Kangaroo type. 10. Bird type, no ilio-ischial angle. 11. Kaptorcs type, ilio- 

 ischial angle reversed. 12. Chelonian type. 13. Saurian type, ilio- pubic angle reversed, and remarkably 

 acute ilio-ischial angle. 



