28 ON MYORYKTES WEISMANNI. 
again, communicated with a tube which became much atte- 
nuated towards its termination. Each of the other two 
fibres presented a single orifice, but only one of these was 
seen clearly to be in connection with a tube which gradually 
narrowed and terminated in a short extremity; the third 
fibre contained no parasite. 
Nematodes were also found in a cylindrical closed sacculus, 
which otherwise differed from the former only in the greater 
thickness of its walls. But this appeared to be merely the 
cast-off outer integument, from which the worm had not yet 
fully freed itself, and which had, probably, become dis- 
tended at both ends by a fluid secretion from the inhabitant. 
On this account the structure might readily be taken for an 
elongated, cylindrical cyst, in close apposition with the body 
of the worm, except at the two ends. 
The same thing was subsequently observed in fresh speci- 
mens. The parasites were on this occasion also seen be- 
tween the fibrille, moving sometimes in a straight, some- 
times in an oblique direction, and always surrounded with 
the above-described delicate pouch, which, from its con- 
sistence, seemed to consist of a viscid or mucous substance. 
The two sexes of the parasites observed in March were 
exactly alike in outward appearance and size. Their 
length was from 0:162—0:216 mm., and breadth 0:0135— 
0:0162 mm. The body was cylindrical, straight, and termi- 
nated at each end, after narrowing, for a short distance, in a 
knob-like, rounded enlargement, which was less and not so 
well defined at the anterior than at the posterior end. 
In the mouth was contained a short, horny rod, termi- 
nating in front in a minute head, and which might serve as a 
boring instrument. A very delicate transverse line in the 
integument immediately behind the oval opening probably 
indicated a fine annular ridge, or an annular series of 
numerous fine tubercles or denticles, but no structure of 
the kind could be clearly made out even with a magnify- 
ing power of 500 diameter. The supposition was suggested 
by the observation that the diameter of the holes in the 
sarcolemma corresponded, for the most part pretty exactly, 
with that of the worm at the situation of this fine line. 
The integument is smooth, and beneath it may be seen a 
ie longitudinal muscular layer. There are no median 
ines. 
The cesophagus is a cylindrical canal, lined with a firm 
structureless membrane. The intestine is lined with a simple 
tesselated epithelium. The rectum is short, and without 
epithelium. The anus is situated a little in front of the 
knob-like caudal enlargement. 
