34 ON A NEW SPECIES OF ENTEROPNEUSTA, 



heart bladder and the proboscis gut, but just behind the anterior 

 ends of these it becomes limited to two lateral masses l3^ing on the 

 heart bladder and the notochord, and to a small median portion 

 on the dorsal side of the heart bladder. This median portion 

 which stands in connection with the lateral portions by vessels on 

 the walls of the heart bladder posteriorly gives rise to two or 

 three large longitudinal vessels which finally unite to form one 

 main vessel (fig. 3, mgl.) which passes obliquely backwards and 

 upwards along the dorsal edge of the heart bladder (fig. 5, esv.), 

 and comes into connection with the capillary net of the proboscis. 

 Yentrally, also, the lateral masses stand in connection with the 

 capillary net by a network of vessels in the ventral septum of the 

 proboscis. According to Spengel, these vessels, dorsal and ventral, 

 probably act as the efferent skin vessels, i.e., they probabl}^ convey 

 the blood from the capillary net of the proboscis to the glomerulus. 

 The glomerulus vessels themselves are similar in their relations to 

 those of Pt. minuta. As Spengel has shown, these vessels 

 represent a honeycomb-like system. As in that species corre- 

 sponding to the floor of the honeycomb there is a sinus on the 

 lateral walls of the heart bladder which communicates with the 

 central blood space by narrow clefts. From the sinus there 

 radiate outwards vessels which, in longitudinal vertical sections, 

 are readily seen to be connected in a net-like manner, and at the 

 periphery of the glomerulus they give rise to a network of mucli 

 larger vessels (figs. 3, 4, 5, 6, gl.). The latter opens into a 

 longitudinal vessel occupying the ventral corner of each half of 

 the glomerulus, and which in this species can be traced to near 

 the anterior end of each half of the glomerulus (figs. 3, 4, 5, epv.). 

 These vessels Spengel terms the efferent proboscis vessels, and 

 according to him they arise at the posterior end of the glomerulus. 

 In this species they certainly become distinct at the posterior end 

 of the glomerulus (fig. 8, epv.), but they can be followed up from 

 here as distinct vessels lying in the ventral corner of each half 

 of the glomerulus to near its anterior end. 



From a comparative study of the glomerulus, and from its 

 histology, Spengel is led to regard the glomerulus as a system of 



