SHAPE AND STRUCTURE OF ALIMENTARY VISCERA OF PORPOISE. 315 



Cavity of Abdomen. — On opening the abdominal cavity by removing the ventral 

 wall, it was found that the general shape of the cavity was oval, the anterior end was 

 more obtuse than the posterior, and the greatest transverse diameter was opposite the 

 lower or hinder border of the liver. The upper (anterior) part contained the liver and 

 greater part of the stomach, while the posterior part was filled by the convoluted mass 

 of the intestine. 



The border of the liver extended across the cavity from a point opposite the eighth 

 right costo-chondral junction to a corresponding point on the left side, in an almost 

 transverse direction ; and near the mesial plane of the body there was a triangular notch 

 which was occupied by a small portion of the wall of one of the chambers of the 

 stomach, while another small part of the stomach wall projected from below the border 

 of the left lobe, but only for three-quarters of an inch. The coils of intestine of were 

 practically the same calibre throughout, and were suspended from the dorsal wall by a 

 single mesial mesentery. There was no sign of a vermiform appendix, or csecum, and 

 no part of the tube showed to the naked eye any of the appearances characteristic of 

 the large, as distinguished from the small, intestine. 



The abdominal cavity measured 36*5 cms. in its long axis, and 19 "5 cms. in its 

 maximum transverse diameter, and at the posterior end it narrowed suddenly, and 

 opened by a definite constricted orifice into an elongated tubular chamber, the 

 representative of a pelvic cavity (PL I. figs. 1 and 2). The aperture was formed by a 

 projecting margin of peritoneal membrane, over which the vasa deferentia turned in 

 their course to the urethra. The diameters of this orifice were 25 cms. in the sag- 

 gital axis, by 1*5 cm. in the transverse, and the depth of the chamber was 7 cms. 

 This tubular peritoneal recess passed between the pelvic bones ventrally, and the 

 vertebral column dorsally, and formed the lining membrane of a chamber, which, from 

 its position, contents, and boundaries, we regard as the representative of a pelvic cavity. 

 The projecting margin on either side corresponded to the brim of a true pelvis. The 

 relations of the viscera associated with the peritoneum confirm the analogy, as the 

 urinary bladder lay between the peritoneum of its ventral wall and the pelvic bones 

 and interpubic ligament, while the rectum descended in relation to the dorsal wall, 

 being supported by a mesentery at its upper or anterior part, but gradually losing its 

 peritoneal investment to end in the anal canal. Hitherto, this arrangement of the 

 peritoneum does not seem to have been recognised as a pelvic cavity, although Turner * 

 in a description of the posterior end of the abdominal cavity of Risso's Dolphin 

 {Grampus griseus), refers to the peritoneum as forming " four csecal pouches," of 

 which the dorso-mesial one apparently corresponds to the pelvic cavity which we 

 have described. 



Peritoneal Folds and Reflections. — The falciform ligament of the liver and the 

 Ligamentum teres were both distinct, and were almost mesial in position. The former 

 disappeared into a vertical slit, 5 cms. in length, in the ventral surface of the liver. 



* Sir Wm. Turner, Jour, of Anat. and Phys. t vol. xxvi. p. 264. 



