BY WILLIAM A. HASWELL. 341 



they cannot have specially to do witli the secretion of mucus. Their 

 structure is almost exactly similar in all essential particulars to 

 that of the papillae on the elytra of the Polynoidae (fig. 18), and 

 I have no doubt that the function is the same in both cases.* 



In Stylarioides ductus the form of the papillae (fig. 15) is 

 similar to that of those of Copping evict ; but each papilla here is 

 situated on the summit of a conical elevation, in which is contained 

 the relatively large basal ganglion. In Stylarioides Horstii the 

 papillae (figs. 17a and 176) are very long and slender, not unlike 

 those of Siphonostomum, but with only a very faint terminal 

 swelling. Each is covered, except at the extreme end, by a very 

 thick layer of tough mucus. In Stylarioides monilifer (fig. 19) 

 the form and structure of the papillae is essentially similar to 

 those of S. cinctus, the basal part being, however, relatively 

 longer. 



V. — Blood-vascular system; branchiae; unpaired gland. 



Considerable discrepancies exist between the descriptions of 

 the vessels in the Ghloraemidae given by different authors. 



Dujardinf simply states that he had seen the green blood circu- 

 late in dorsal and ventral longitudinal vessels with numerous 

 transverse branches. 



CostaJ describes the ventral vessel ("vaisseau abdominal ou 

 veineux ") in Lophiocephalus as not extending through the length 

 of the body and not adhering to the body-wall, but as free, arising 

 from the lower part of the oesophagus, increasing in size as it 

 extends backwards, attaching itself to the walls of the stomach, 

 again becoming reduced in size and losing itself in ramifications 

 on that organ as well as on the wall of the body. From the 

 ventral vessel it passes to the branchiae, by which it returns 

 through the dorsal vessel or heart, which in turn breaks up into 



* Vide Jourdan, "Structure des elytres de quelques Polyuoes," ' Zool. 

 Anz.,' 8, p. 128. 



+ L.c. (8). 

 JL.C. (6). 



