228 E. A. ANDREWS. 



Wijhe (32), who regards it as of excretory function. It seems to be 

 much less complex than in the European form ; though it presents 

 some branches anteriorly it is not to be regarded as a glomus 

 here. Posteriorly it passes between the velum and the lateral 

 muscles but could not be traced into connection with other vessels. 

 Anteriorly it passes between the walls of the pit and the azygos 

 ridge, close to each end bends up dorsally between the tip of the pit 

 and the end of the ridge. Here it immediately unites, at the an- 

 terior end of the pre-oral chamber, with a large branch of the left 

 aorta, forming thus a median aortic trunk that runs forward a 

 short distance, close beneath the notochord, bifurcates, and ends in 

 the ventral sheath of the notochord. This left aorta is notably 

 smaller than the "right arch" (Figs. 12, 13) and branches just 

 before the anterior end of the pre-oral chamber is reached, sending 

 the larger branch to fuse with the " right arch," as above stated, 

 and the smaller branch forward a short distance to branch in turn 

 and, perhaps, to connect with the large median lymph space begin- 

 ning here and lying under the notochord as seen in Fig. 10. 



Of the two aortic trunks found in the pharyngeal region it is 

 only the left that connects, as above, with the " right arch." The 

 right aorta seems to disappear in the velum. 



No attempt has been made to trace out the rest of the vascular 

 system though the chief aortic trunk, the vessels of the branchiae, 

 and the numerous vessels on the posterior intestine and caecum seem, 

 in sections, to be much as described for the common Amphioxus. 



The branchial apparatus is like that of the known forms ; but 

 as seen in Figure 2 the first gill-slit may be small and only partly 

 divided by a tongue bar, while in the European species van 

 Wijhe (32) finds that the first gill slit has no tongue bar. In 

 macerations of the branchial skeleton we find the usual primary 

 bars and tongue bars represented by rods that are double in the 

 former, divaricating at the lower end and deeply cleft lengthwise, 

 but apparently single in the latter, though marked longitudinally 

 by cavities and grooves. 



Primary rods and tongue bar rods unite dorsally, so that they 

 form a series of three-tined forks. 



The usual number of horizontal connecting bars pass across the 

 tongue bar from one primary to the next. Dorsally the processes 



