1895.] Zoology. 755 
and aslender ventral portion, from which the terminal duct arises. 
The intra-cellular canal is very tortuous, and in part seems to form a 
plexus such as has been described for other Enchytræidæ by Bolsius. 
Nuclei are prominent, but cell divisions in the granular protoplasmic 
mass, not apparent. No spermatheca have been found. 
The essential sexual organs occupy the usual positions. The funnel 
of the vas deferens is rather small, with an oblique, ventrally directed 
mouth. Its duct is slender, closely coiled entirely within the twelfth 
somite, and about five or six times the length of the funnel. It termi- 
nates in a copulatory apparatus exactly like that of the Fridericia ex- 
amined, that is, the duct perforates the muscular sheath of the spheri- 
cal prostate gland, which is composed of radiating pyramidal cells, and 
opens immediately dorsal to the mouth of the gland into a tabular in- 
vagination of the body wall (atrium), which can be everted to serve as 
a penis. The oviducts have the usual form and position. 
Peritoneal corpuscles are of two kinds, the smaller ones being about 
half the diameter of the nuclei of the large ones, elliptical and refrin- 
gent. 
The supra-cesophageal ganglion is truncate or slightly concave poste- 
riorly and varies in relative length. 
The dorsal blood vessel arises from the sinus in somites xiii and xiv 
and hence is post-clitellian. There is an internal chain of valve cells, 
not, however, very greatly developed. The only other peculiarity of 
the vascular system is in the structure of the endothelium bounding 
the peri-enteric blood sinus, which requires further study. 
The above is an abstract of a detailed account which was prepared 
with appropriate figures last winter, but which has been withheld in 
the hope that an acquisition of fresh material would permit the eluci- 
dation of several doubtful points. 
The material on which this account was based consisted of several 
rather poorly preserved specimens found among the collections left by 
the late Dr. Joseph Leidy at the University of Pennsylvania. 
The several points referred to above about which I am still in doubt 
are the character of the spermathece, if present, the presence or ab- 
sence of dorsal pores, the minute structure of the nephridia, and the 
number of species, there being indications of the existence of two. 
Furthur studies of the variations and distribution of the setz are also 
desirable. | 
Michaelsen, in his synopsis, has placed Distichopus next to Frideri- 
cia, but apparently without any intention of suggesting relationship. 
That such a relationship exists, and that Distichopus finds its closest 
