152 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. [1885. 



licular artery /r at the outer border of the thickened edge of the mem- 

 brane. 



The yelk 2/, liver I, intestine i, i.^ i, the air-bladder a&, the Wolffian ducts 

 Wd, Wd, the aorta ao, chorda ch, muscles of the pectoral pf, &c., are also 

 shown in Vig. 9, But in order to comprehend the visceral anatomy of 

 the foetal stages of Gambima, Figs. 5, 6, 7, 23, and 25 are more sat- 

 isfactory. 



These sections will render it obvious once for all that in this form at 

 least there is no connection whatever of the yelk with the intestine. 

 That there is a wide space, sc, between the intestine posteriorly and the 

 vitellus y is plainly shown in Figs. 5, 0, and 7. 



The yelk also presents a well-marked periblastic layer, yh, in which 

 the oil globules are embedded superficially. This peribla.stic stratum 

 is thickest on the outer surface of the yelk and in the vicinity of ves- 

 sels, but quite thin where it forms the floor of the abdominal cavity- 

 In the cross-section. Fig. 5, the periblast sends up a median s^ptumi 

 which divides the cruder yelk or deutoplasm into two moieties. Super- 

 ficially the periblast has the vitelline vessels impressed into its surface., 

 and in consequence of the fact that I have been unable to find a distinct 

 cellular wall on their inner or periblastic sides I infer that the yelk is 

 taken up from the periblast directly by the vessels. The cleavage 

 cavity is persistent as in other Teleosts, and is apparent on either side 

 of the vitellus in Fig. 9. 



The heart, the details of which are shown in transverse section in 

 Fig. 8, extends down into the anterior end of the yelk-sac, as shown in 

 Figs. G and 7, having been first extended into the cleavage cavity, as 

 indicated in Fig. 13. The most inferior chambers of the heart receive 

 the venous blood, and all are thin walled except the ventricle ve and 

 the bulbus aortie ba.. Fig. 6. The heart, as well as the liver and intes- 

 tine, is more or less impressed into the surface of the yelk. 



The oesophagus is somewhat bent upward posteriorly, from which ex- 

 tremity the air-bladder arises somewhat to one side. The pneumatics 

 duct is open hi the foetus and is short, leading abruptly into the air- 

 bladder ah, which is a depressed sac, the floor of which is very much 

 thicker than the roof. The liver is a very massive organ relatively, and 

 opens into tbe alimentary canal in the vicinity of its fir.-t turn. A 

 large i)ortal vessel passes from the liver outwards to the left, as shown 

 in Fig. 5, and communicates with the vitelline system of vessels. What 

 seems to represent a pancreas is seen in some sections adherent to the 

 intestine, as shown in Fig. 6. In the posterior and upper part of the ab- 

 dominal cavity, behind the intestinal coil, are placed the reproductive 

 organs o, as indicated iu Figs. 6 and 7; with greater magnifie;i<ion of 

 that part of a cross-section the reproductive organ or genital folds have 

 the appearance indicated at in Fig. 25, which shows the organ in its 

 indifierent stage, when it is quite impossible to tell whether the large 

 uncleated cflls embedded in it are going to give rise to ova or to sperma- 

 to;?oa. They lie on either side of the mesenteric suspensor of the intes- 



