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 lying 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, esvX 
and comes into connection with the capillary net of the proboscis. 
Ventrally, 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 probably 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 much 
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 
