366 
Ascarids in the British Museum 
It will be necessary to give a brief redescription of tbe Challenger 
specimens in order to substantiate tbe new determination; and this will, 
it is hoped, at the same time give further support to the view that 
A. decipiens is the adult form of the true “A. capsularia.” 
The male (of which there is now only one example) is 50 mm. in 
length, and 2 mm. in thickness. The females measure 67-90 mm. in 
length, and 2-2-5 mm. in thickness. The cuticle, quite smooth to the 
naked eye, is seen under the microscope to be marked with minute 
transverse striations only 2-5 g apart, and thrown into larger wrinkles 
at about every thirteenth striation, but somewhat irregularly. At 
about 0-7 mm. from the anterior end there is a pair of rather large, 
conical cervical papillae. 
The lips (PI. XVI, fig. 3) conform much more closely to Krabbe’s 
figure of the lip of A. decipiens (1878, PI. I, fig. 3) than to that of 
A. simplex ( l.c. Fig. 4). I am at a loss to understand how, with the 
Challenger material before him, von Linstow was led to make his figure 
(1888, PL I, fig. 2) so nearly a copy of Krabbe’s figure of A. simplex. 
I also find the closest agreement between the shape of the bps in the 
Challenger specimens and that shown in the original drawings of 
A. decipiens given by Stiles and Hassall (1899, Figs. 10-14). The 
anterior, bilobed portion of each lip spreads out laterally at each corner 
in precisely the manner figured by Krabbe and the American authors, 
and is of quite a different shape from that of A. simplex. The dorsal 
lip is more upright, when seen from the anterior aspect, than the two 
ventro-lateral lips, and its bilobed portion has a more distinct “neck.” 
The bilobed portion of the dorsal lip is slightly narrower than that of 
the other bps (0-19 mm. < 0-21 mm.), but the basal part is actually 
broader (0-28 mm. > 0-25 mm.). From the measurements given by 
von Linstow it would seem that he must have mistaken the “neck” of 
the bilobed portion of the dorsal hp for its basal part; an error that 
might easily occur when viewing the bps in optical section. The width 
of this “neck” is about 0-13 mm. A dentigerous ridge is present near 
the edge of each hp, as stated by all the authors. There are no 
interlabia. 
The tail of the male (PI. XVII, fig. 2) is considerably widened out 
laterally, the widest part being about 3 mm. from the tip of the tail. 
The edges are prominent muscular ridges rather than cuticular alae, and 
are normally drawn inwards towards the mid-ventral line, so that a 
transverse section in this region of the body would show a concavity 
on the ventral side. For rather less than 1 mm. from the tip, the 
