44 NILS HJ. ODHNER, STUDIES ON RECENT CHAM1DAE. 



In the duodenum the two furrows are situated in such a way that the narr- 

 ower one lies on the left and the broader on the right side; the latter widens down- 

 wards and passes into the intestine by a single turn. The intestine is somewhat 

 thicker in its median part. 



The circulatory system. The ascending branch of the anterior aorta, af ter 

 its exit from the bulbus, traverses the liver on the left side of the stomach beneath 

 the intercardinal lamella of the mantle. It descends again on the left side of the 

 oesophagus and then into the foot. The ascending branch also sends a small vessel 

 to the right side of the body which irrigates the liver and the genital organs in 

 that part. The descending aorta trunk penetrates the liver and arrives at the left 

 side of the stomach, where it bifurcates and encircles it from behind. Under the 

 stomach it dissolves into smaller vessels, which ultimately disappear among the 

 viscera. 



The nervous system is of the same type as in other forms of P ' seudochama ; 

 the cerebro-visceral connectives run through the liver about half-way between the 

 stomach and the exteriör surface of body. 



The gills are constructed in much the same way as in Echinochama, with the 

 exception that no direct axio-marginal vessels exist in the higher venous septa ; 

 the latter alternate with the lower ones and with arterial septa of a still smaller 

 height quite as in Echinochama. The folds of the gills each contain about 23 fila- 

 ments. 



The kidneys (figs. 48, 49). As a consequence of the posterior deflection of 

 the body from its substratum, the right insertion of the posterior adductor has a 

 more posterior position than the left one; a corresponding obliquity of the nephridia 

 can, of course, be established. Both these organs, however, just as the intestine, 

 are placed nearer to the left than to the right side of the body. The right ne- 

 phridium is produced somewhat higher than the left one. The open pericard grows 

 narrower downwards ultimately forming two lateral corners. From the apices of 

 these emerge the pericardial tubes. The ciliated funnels converge in an acute angle, 

 widen to a somewhat more spacious ampulla with folded walls lined with small 

 ciliated cells; from these ampullae the remaining parts of the tubes are directed 

 upwards acquiring a rather broad shape, and reach as far as the upper end of the 

 nephridia where they pass into the outer sacs. The pericardial tubes have their 

 median sides uncovered, not until they diverge again on the back side of the outer 

 sacs are they overlapped by some lobes of the latter. These, consequently, do not 

 completely surround the pericardial tubes, but cover them only outside. The walls 

 of the outer sacs have shallow lobes. A narrow mutual communication exists above 

 the nephrostomes, and below and outside them the nephroprocts open, opposite to 

 the genital pores. 



In this species, consequently, the nephridial apparatus has, for the most part, 

 been displaced över to the left side. 



The genital pores are situated on small papillae opposite to and somewhat 

 above the nephroprocts. 



