32 ON A NEW SPECIES OF ENTEROPNEUSTA, 



and the underlying ciliated grooves, and into a posterior caudal 

 region. 



In the abdominal region the ciliated grooves may be situated 

 directly under the epidermal stripes or may be remote from it by 

 a short distance, but always the portion of the longitudinal 

 musculature between them is somewhat thinner than elsewhere. 

 The cells of the epidermal stripes usually stain darker, and are 

 somewhat lower than the adjacent cells, and in one case where the 

 grooA'e was situated immediately under the epidermal stripe there 

 existed what appeared to be a special differentiation of the cells 

 of the latter in the form of a small mass of cells with rounded 

 nuclei and distinct nucleoli. In other respects the abdominal 

 region of this species closely agrees with that of Pt. minuta. The 

 wall of the gut in this region (fig. 25, i.) is thrown into numerous 

 somewhat irregular transverse folds, and it becomes further removed 

 from the longitudinal musculature so that the coelom is very much 

 more distinct than in the liver region and, as there, divided into 

 two distinct halves only, however, in the anterior part of the 

 region. The band-like cellular mass which 8pengel has found in 

 Pt. minuta and sarniensis in connection with the dorsal vessel and 

 lying along the dorsal median line of the gut also exists in this 

 species. It has here the form of a low band of cells of varying 

 height lying as in the described species between the two lamellae 

 of the boundary membrane of the gut and not limited laterally. 

 Between the dorsal vessel and the cellular mass there passes a 

 short mesentery, and by the separation of this into two lamella? 

 the cavity of the dorsal vessel comes into direct connection with 

 the cellular mass. At these points the cells of the mass are not 

 closely packed, and have a branching character exactly like the 

 endothelial cells of the dorsal vessel with which they seem to be 

 continuous. 



The caudal region of the hind body is essentially similar to that 

 (jf Pt. minuta. As in the posterior part of the abdominal region, 

 the two halves of the coelom here stand in connection below the 

 dorsal vessel. On the ventral side the ventral vessel disappears 

 as a distinct structure at the beginning of this region, while the 



