362 
Ascarids in the British Museum 
Ascaris capsularia Rud. s.s. 
(PL XIV, figs. 1-3; PL XVI, figs. 1-2.) 
Rudolphi (1802), p. 27. 
Diesing (1851), p. 163. Also Agamonema capsularia, p. 116. 
Baird (1853), p. 22. 
For other literature and synonymy, see Stossich (1896). 
A number of immature Ascarids in the British Museum collection, 
bearing various determinations on the labels, have been examined and 
critically compared with a view to arriving at a clearer conception of 
their real status. The result of this investigation is that the majority 
of the immature forms from fishes are found to be referable to the same 
abundant species; some have been correctly named Ascaris (or Agamo¬ 
nema) capsularia, others under names such as Agamonema commune 
should be included under A. capsularia, while others, again, though 
labelled capsularia, should be set aside as incorrectly determined and 
probably belonging to one or another distinct species. The majority 
may unquestionably be referred to the true A. capsularia, and the 
following is an attempt to describe that so-called “species” with a 
somewhat greater degree of precision than has hitherto been done. 
The specimens vary from about 9-38 mm. in length, and from 
0-22-T0mm. in maximum thickness. (Care must be taken with these 
encysted forms to distinguish between the actual outline of the worm 
itself and that of the one or more cast-off cuticles which generally 
surround it. These are not reckoned in the above given measurements 
of thickness.) 
The cuticle is, for the most part, smooth. Near the tail-end, however, 
it is usually marked with fine transverse striations, the distance between 
which varies with the age of the individual. In the younger stages the 
mouth appears to be occluded by the cuticle. The extremity of the head 
(Pl. XVI, fig. 1) is provided with a conical boring-tooth ( T .), situated 
in the position subsequently occupied by the left vent.ro-lateral lip, 
and usually bent strongly towards the ventral side. The three bps are 
at first scarcely visible, or can only be distinguished very vaguely 
beneath the cuticle of the head. At a later stage the boring-tooth 
becomes greatly reduced in size in proportion to the hps, which are 
more readily seen. None of the stages found in fishes, however, exhibit 
any structure of the lips which enables them to be definitely referred 
to any one adult species. 
