ON ARHYNCHUS HEMIGNATHI. i | 
the number of nuclei is very small, some twelve to twenty seem 
to suffice for the whole of the subcuticle, and perhaps two to 
four for each lemniscus. The structure of the nucleus shows a 
most striking resemblance to an ameeba with rather short pseudo- 
podia (figs. x, x11, and xtv)._ No single nucleolus can be de- 
tected, but numerous chromatin particles are present, and 
in some a distinct vacuole can be observed. These nuclei are 
scattered about in a most irregular fashion ; not one may be 
seen in a number of consecutive sections, and then perhaps 
three or four may appear, and from their large size persist 
through several sections. The nuclei lie, as a rule, embedded 
in the substance of the subcuticle ; more rarely they are found 
in the lacunz. Although there is no proof, one is tempted to 
believe that the nuclei wander through the subcuticle and 
lemnisci in an amceboid manner, and that the small number of 
nuclei which are found in these tissues is compensated for 
partly by the large size of each, but more especially by their 
mobility. Similar amoeboid nuclei undoubtedly move about, 
fuse with one another, and undergo fission in the subcuticle of 
the larval forms of Neorhynchus claveceps. 
Within the subcuticle and completing the skin on the inner 
side, is a layer of circular muscles, and still more internally a 
layer of longitudinal muscles (figs. vi and xv). The muscles of 
these layers are but a single fibre thick, and they are not very 
uniformly present. The circular layer is most complete in 
the region of the trunk, and I have figured a section to show 
this (fig. x11). The longitudinal layer is even less definite, 
but scattered fibres can be detected here and there (figs. xiv 
and xv). Hach fibre appears to be spindle-shaped, and in the 
circular muscles has the striated portion only on its outer face, 
forming a thin band; the inner half of the fibre consists of 
vacuolated strands of protoplasm in which is a nucleus. The 
longitudinal layer of muscles alone is continued over the 
lemnisci (figs. 1x and xiv). These muscles are not covered 
on their inner side by any layer of epithelial ceils, neither 
does any such layer cover the ligament, but both tissues lie 
freely exposed to the fluid of the body-cavity. 
