760 THE AMERICAN NATURALIST. [Vor. XXXVI. 
above the base of the cirrus and not, as has sometimes been 
described, beneath it. In section the caudal cirrus shows the outer 
epithelium, a thin circular and comparatively strong longitudinal 
muscular layer, and a zone of mesenchyme cells surrounding a large 
central blood space. The two lateral nerves are here situated in the 
outer epithelium, the outer longitudinal muscular layer and cutis 
being absent. Neither do the gonads, intestine, nor proboscis sheath 
continue back into this organ. This description agrees closely with 
the characters given by Punnett for the caudal cirrus of Micrella 
rufra, except that he finds only rudimentary blood vessels. 
The distribution of cutis glands has been very fully studied. A pair 
of neurochord cells was found in the ventral ganglia. A longitu- 
dinal groove on each lateral margin of the body just anterior to 
the intestinal region is looked upon as a sense organ which may 
be homologous with the lateral sense organs recently described by 
Punnett for Micrella,? where they are situated just back of the 
excretory pore, as are the well-known sense organs in Carinella. 
Blood lacunz were not found anterior to the brain; lateral blood 
vessels are united at intervals below the cesophagus. A large lacuna 
without definite walls passes into the caudal cirrus. Parasitic greg- 
arines were found in the intestinal epithelium and in the ova. 
Infected eggs grew to several times their normal size. 
The evidence that the genus Zygeupolia should be placed among 
the Lineidz seems conclusive, the only feature distinguishing it 
from other members of the family being the absence of cephalic 
furrows. It is rightly regarded as the most primitive or aberrant mem- 
ber of that family which has yet been described. With Punnett’s 
new genus Micrella there is certainly a close relationship, and both 
forms serve to bridge over the gap between the Eupolida and the 
Lineide. In many points of anatomy the two genera are very 
similar, and while in Zygeupolia the cephalic furrows are wanting, 
yet an approach to this condition is found in Micrella, where the 
furrows reach only half way to the brain. Punnett's new genus 
Oxypolia likewise forms a connecting link in the series, although 
this clearly belongs to the Eupolidz, being more closely related to 
Valencinia. W. R. C. 
! Punnett. Quart. Journ. Micr. Sci., vol. xliv (1901), p. 553- 
? Punnett. Loc. cit., p. 551. 
