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Parasitic Worms 
been in some directions perhaps a tendency to excessive sub-divisions, 
the systematic work has been of the greatest value and has served as 
a basis for, and criterion of, work done in other departments. 
Most of the works above-mentioned have dealt at the same time 
with faunistic and morphological questions. Very large additions have 
been made to the number of known species, but in consideration of the 
fact that only a few circumscribed regions have as yet been thoroughly 
investigated and that even in Europe new forms are constantly being 
discovered, it is evident that an enormous amount of parasitic material 
remains unknown. Outside Europe it is only in the United States and 
in the Nile Valley that a serious attempt has been made to study the 
parasitic fauna in general. It may be added, however, that a good 
beginning has been made in Australia by Miss Sweet, and T. H. and 
S. J. Johnston. Asia and South America remain practically untouched. 
Of morphological matters only a few of the more interesting can be 
discussed here. One of the most remarkable of these is the discovery 
by Odhner (1910) of a gigantic blood-fluke in the blood vessels of 
a gull. It is a form closely related to the well-known human blood- 
fluke, but it is remarkable in possessing no suckers. This may be 
interpreted as an adaptation towards its mode of life, and such a 
view is borne out by the discovery of another blood parasite, possessing 
the same peculiarity, but not otherwise at all closely related to the 
former, namely Sanguinicola, a parasite of fishes. By its discoverer it 
was at first regarded as a Turbellarian and later as a Monozootic Cestode. 
A separate order, indeed, was created for its reception. Odhner (1911), 
however, showed that it is in reality a digenetic Trematode, and that 
a closely related form, Aporocotyle, was known as long ago as 1900. 
Further interest in this matter has been stimulated by Linton’s discovery 
of a similar form, Deontacylix , in an American fish. All these forms 
present a great resemblance to Monozootic Cestodes but differ from them 
in possessing an alimentary canal. Another remarkable discovery in 
Trematode anatomy was made by Leiper (1908) to the effect that in 
a curious new avian Echinostome ( Balfouria ) there is communication 
between the intestine and the excretory bladder. This observation was 
confirmed by Odhner (1910), who found the condition present not only 
in Balfouria but also in another allied species, and in a widely different 
genus of fish Trematodes ( Haplocladus ). A further case is reported by 
Looss (1912). Odhner interprets the condition as the formation of 
a secondary anus. This discovery will involve a revision of the generally 
accepted belief that the Trematode intestine usually ends blindly, and 
