386 PROCEEDINGS OF THE ACADEMY OF [^lay, 



tudinal trunk muscles; while the walls of the vestibulum have a rich 

 network of muscles. There are three pairs of large visceral longitudinal 

 muscles (figs. 22, 23, 25, 27, 28), a pair of dorsal {D.M.), of lateral 

 (L.M.) and of ventral (V.M.) muscles respectively, attached anteriorly 

 to the coronal margin, passing the whole of the trunk and in the foot 

 converging together to form a muscle band which extends posteriorly 

 as far as the proximal end of the peduncle (fig. 40); the cell bodies 

 (Musc.C.^ fig. 28), and nuclei of these large muscle cells are placed 

 within^the foot. Probably the proventriculus has its proper muscula- 

 ture, thought it could not be determined ; and the muscles of the oesoph- 

 ageal tube have been already mentioned. 



Nephridial sijstem.— This is essentially the same in conklini (fig. 25), 

 campanulata (28, 30, 41) and coronetta (figs. 22, 23). Opening into the 

 posterior end of the cloaca is an unpaired, thin-walled contractile vesi- 

 cle (Con.V.), and into this an unpaired contorted canal enclosed by a 

 membrane. From the proximal end of this canal pass forward the 

 two longitudinal canals, one on each side of the trunk, a httle more 

 ventral than dorsal in position. The anterior portion of each of these 

 canals becomes convoluted, and tliis convoluted portion is thicker than 

 the rest of the duct with a narrower lumen, and somewhat contractile. 

 It is only by continued study of compressed hving individuals that the 

 bendings and interlacings of these very transparent canals can be deter- 

 mined. Anteriorly each longitudinal canal gives off an anterior and 

 a posterior ductule. Each anterior ductule divides close to the lateral 

 wall of the corona into three secondary ductules, each terminating in 

 a single flame cell (Fl.C). The posterior ductule passes caudad to 

 about the region of the oesophageal tube on the side of the body, then 

 divides into two secondary ductules, a shorter dorsal one ending in a 

 flame cell on the side of the mastax, and a longer ventral branch ter- 

 minating in another flame ceU on the latero-ventral aspect of the trunk. 

 In conklini I could not ascertain the mode of union of the ductules 

 with the lateral canals, on account of the large number of those floating 

 corpuscles within the body cavity which greatly obscure the nephridial 

 organs. F. ambigua (fig. 21) differs from the preceding species in 

 having six flame cells and ductules on each side of the body, i.e. an 

 additional one near the anterior end of the longitudinal duct. 

 Amhigua also differs from the other forms in having the membranous 

 tube which encloses the posterior unpaired canal much longer than in 

 the other species; but I did not have sufficient material to determine 

 its exact length. Only in coronetta (fig. 23) is there an anterior com- 

 missure joining branches of the anterior ductules of the two sides of 



