ART. 14. A NEW MERMITHID WORM FROM JAMAICA STEINEE. 6 



But this is not tlie only peculiarity in the structure of the head- 

 end. Whereas the mouth opening is shifted backward and down 

 from the top of the head, two other organs, namely the amphids, are 

 shifted forward and nearer to the top of the head. These amphids 

 lie throughout the nematode class laterally behind the head papillae. 

 As far as I know only the above-mentioned Paramermis, species 

 which have a shifted mouth opening, have also shifted amphids: in 

 these species they are found on the same level with the head papillae 

 or even a little farther forward. But Alloniermis trichotopson rep- 

 resents in this transformed ari'angement the extremest case, the 

 mouth opening located farthest caudad, the amphids, farthest for- 

 ward. There are four submedian head papillae situated at the 

 normal place. 



The mouth ojDening is a rather narrow, thin-walled channel 

 through the cuticle and lower subcuticle layers, leading to the begin- 

 ning of the cutinized esophageal channel (fig. 1). The latter at its 

 beginning is dorsally attached by a rather strong muscle passing 

 obliquely caudad and dorsad. This muscle certainly functions in a 

 double way, as suspensory muscle for the end of the esophageal 

 channel and as a retractor muscle. A protractor muscle is appar- 

 ently not needed because of the elasticity of the skin, the exoskeleton. 



The amphids are, as shown in Figure 6, pouch-like organs; the bot- 

 tom of the pouch is connected with a nerve and with what seems to 

 be a glandular cell; from the bottom of the pouch, which is per- 

 forated, rise the terminals, thread-like end organs of the nerve, 

 which are perhaps chemical in function. 



There is a difference between the amphids of the male and female 

 in so far as those of the male are larger ; such a sexual dimorphism 

 is not uncommon among Mermithids. 



The length of the esophageal tube could not be determined, but it 

 probably runs down to near the vulvar opening; I could follow it 

 near to the midst of the anterior uterus. 



The so-called fat body is filled with rather small glolniles so that 

 the cell walls even in the cleared specimens could not be distinctly 

 seen. Opposite the vagina the fat body was separated, perhaps to 

 give space to the sexual organs. 



The vulva is a cross-fissure (fig. 7) leading into a tubular sigmoid 

 vagina bent in a transverse plane of the body. Numerous, chiefly 

 circular, but also longitudinal, muscle fibers form the wall of the 

 vagina. This latter opens at right angles into the uteri which are 

 outstretched forward and backward. The structure of the two 

 ovaries and their outlets could not be seen, but each ovary is bent 

 backwards and its end may lie at half the distance to the vulva. A 

 great number of very typically formed eggs were in the uteri. They 

 were spherical, had a rather strong shell covered witli numerous 



