4 THOS. H. MONTGOMERT, 



this elongated form, with posterior truncation, except in Prosorhoch- 

 mus claparedii (cf. the figure in M'Intosh's "Monograph") ; 2) in tlie 

 large number of the ocelli; 3) in the presence of subepithelial gland 

 cells in the head. In regard to the other points in its structure, it 

 resembles ÄmpMporus. In one point it diflers sharply from all other 

 Metanemertean genera: the shortness of the proboscis, in connection 

 with the length of the rhynchocoel. Verrill, who first described 

 this species, assigned it to ÄmpMporus ; the notes on its 'anatomy, 

 which I have given, demonstrate that it should be placed in a new 

 genus. 



Not only is Zygonemertes intermediate between Eunemertes and 

 AmpMporus, but also between Bürger's ("Monographie", 1895) groups 

 of the Holo- and ProrJiynchocoelia, since it unites a very short pro- 

 boscis, with a long rhynchocoel ^). 



■*^ 



3. JProneurotes multioculatus n. g, n, sp, 



The lateral nerve chords unite posteriorly below the intestine, 

 about 1 mm anterior to the posterior end of the body ; both rhyncho- 

 coel and blood vessels are continued for some distance behind this 

 nerve commissure (Fig. 27). In no other Metanemertean do the 

 rhynchocoel and blood vessels extend posteriorly as far as this com- 

 missure ; and in probably all others of this group, the commissure lies 

 above the intestine. Anteriorly, the lateral chords lie at the latero- 

 ventral sides of the body. 



The rhynchocoel is voluminous, and extends to the posterior end 

 of the body. Characteristic for this new genus are the unpaired 

 diverticula, 5 in number, which are evaginations of the ventral side 

 of the rhynchocoel, and terminate as culs-de-sac. Two of them (the 

 2i'i and ?>'^^ ) course posteriorly, the remaining three, anteriorly ; and 

 3 of the 5 lie in the posterior quarter of the body. The 4 anterior 

 evaginations have a length of from ^i^r to ^Jo of an inch, the ö*-'' 

 (most posterior) is more than four times as long as any of the others, 

 with a length of about -^^ of an inch. The cavity of the 5'^ attains 

 a diameter of about one fourth that of the rhynchocoel, while the re- 

 maining four have only about ^2 to Vs the diameter of the 5th. 

 The latter differs from the preceding four, also, in that, while it 

 arises from the ventral side of the rhynchocoel, as the others do, it 



1) The structure of the Nephridia is explained in the postscript 

 on page 12. 



