462 SCHULTE, SEI WHALE. 



trally and strongly convex dorsally. Its length is 32 mm.; its greatest breadth is 8 mm. 

 Caudad it tapers to the urethra, the diameter beginning to be reduced from the level of the 

 ureteral orifices. At about this level dorsally the peritoneum is reflected from it upon the 

 uterus and broad ligament. Ventrally it is loosely adherent to the abdominal wall. At the sides 

 the hypogastric arteries are closely united to its walls and the three structures are enclosed 

 within a common sheath, which Daudt finds to be muscular. At the umbilicus the arteries 

 have a dorsal position, the urachus ventral. The muscularis is very thick, the lumen is reduced 

 to a narrow cavity. The mucous membrane is thrown into longitudinal folds, of which three 

 are conspicuous; a mid-dorsal one beginning between the ureteral orifices, and two more lateral 

 in position, in line with the ureteral elevations and approximated to them in the manner already 

 described. The latter are continued to the junction with the urachus. The median fold 

 diminishes rostrad, and gives place to two folds one on each side, intermediate between it and the 

 lateral folds. Ventrally there is a low median fold. As more numerous and less definitely 

 arranged folds are described by Daudt in older fcetuses, it is to be concluded that in the bladder 

 as in the alimentary tract in general a few primary folds are secondarily replaced in develop- 

 ment by more numerous and smaller ones. 



Urethra. The urethra is very long having a length of 23 mm. to its external orifice. Its 

 external diameter is 3 mm. Its lumen stellate at its junction with the bladder gradually becomes 

 a transverse slit as it is followed distad. Near its termination it is about 1 mm. in breadth. 

 Its dorsum is flattened against the vagina. The two are contained in a common fibrous sheath, 

 but only near the orifice could I find the urethra surrounded by the circular muscle layer of the 

 vagina. 



Ovaries. The ovaries rest against the lower poles of the kidneys. Ventral to them are 

 the uterine cor'nua, which the elongated ovaries cross obliquely so that their rostral poles are 

 nearer the median plane than their caudal. Only a small portion of the ovary is caudal to the 

 horn of the uterus and rests against the broad ligament. Rostrad of the cornu the left ovary 

 rests against the hypogastric artery and bladder, the right against the artery without touching 

 the bladder. Their position is thus slightly asymmetrical, the right ovary being somewhat more 

 ventral and rostral than the left, but not more than 2 mm. in either direction. The ovaries are 

 elongated, tapering at their rostral poles, more bluntly rounded caudad, attaining their great- 

 est breadth transversely just caudad of the uterine cornua and their greatest dorso-ventral thick- 

 ness just rostrad of them. In these three dimensions the right ovary measures 10.5 mm., 5 mm., 

 and 3 mm. respectively, the left 10 mm., 4.5 mm., and 3 mm. The surface shows many small 

 pits and shallow sulci which cut it up into polygonal areas. The ventral surface is deeply con- 

 cave to receive the uterine cornu. The convolutions of the oviduct are laterally placed and the 

 summit of its fimbriated extremity is attached to the rostral pole of the ovary. The true and 

 false ligaments about the ovary in Balcenoptera have been described by Beauregard and Boulart ' 

 and studied in more detail by Daudt 2 in B. musculus. Their condition in this foetus agrees 

 closely with the findings of the latter investigator. Each ovary has a slit-like hilus along its 

 lateral border, which deepens caudad and here gives passage to the ovarian vessels, contained 

 in a process of the broad ligament. This fold which is very short constitutes the mesovarium. 



1 Beauregard et Boulart. Recherches sur les appareils genito-urinaires des Balaenides. Jour, de PAnat. et de la Phys., An. XVIII, 

 1882. 



- Daudt, W. Beitrilge zur Kenntnis des Urogenitalapparates der Cetaceen. Jena. Zeitsch. f. Naturwiss., Bd. XXXII, 1898. 



