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BULLETIN OF THE UNITED STATES FISH COMMISSION. 
lorica lias several excavations, and that the toe is very long. Other characteristics must be 
judged from the figure (pi. xv, fig. 146.) 
Heterognathus tarachydacty la Schmarda (1859). 
This species is so inadequately described as to be quite unrecognizable, so that it will have to 
be dropped completely. 
Heterognathus notommata Schmarda (1859). 
Insufficiently described for recognition. The figure bears a slight resemblance to Diurella 
tenuior Gosse. 
Heterognathus diglenus Schmarda (1859). 
This was not one of the Sattulidce, but a Diglena, apparently Diglena catellina Ehr. 
DISTRIBUTION OF THE RATTULID/E. 
As an examination of the foregoing list will show, of the 36 well-established 
species 25 have been found in America and 32 in Europe. Four species described 
from America have not yet been found in Europe; these are Diurella insignis Her- 
rick, Rattulus multicrinis Kellicott, R. mucosus Stokes, and R. bicuspes Pell. | 
Eleven European species have not been found i n America, namely : Diurella rousseleti 
Voigt, D. dixon-nuttalli Jennings, D. sejunctipes Gosse, D. collar is Rousselet, D. 
helminth odes Gosse, D. marina Daday, D. brevidactijla Daday, Rattulus lophoessus 
Gosse, R. stylatus Gosse, R. curvdtus Levander, and R. dub-ms Lauterborn. 
It is not improbable that all the species found in Europe will in time be found 
in this country, and that future workers in Europe will detect the four American 
species there. It was only within a few years that Rattulus latus Jennings was 
described from the United States; it was soon after found by Stenroos in Finland. 
Several of the species described in this paper for the first time are shown to be 
distributed in both Europe and America. Ten of the species here listed from 
America were not known hitherto to exist in this country. 
Some of the better-known species are shown to have a very wide distribution. 
For example, Diurella tigris Muller lias been found widely distributed in Europe 
and America and in India, New Guinea, Natal, and Ceylon. Diurella tenuior Gosse 
has been found in New Guinea, Natal, and New Zealand, as well as in Europe and 
America. Rattulus carinatus Lamarck is recorded from all parts of Europe and 
the United States, and from New Guinea, Ceylon, and Australia. It is probable 
that the group as a whole will be found to have a cosmopolitan distribution. 
Of the 25 American species 23 have been found in Lake Erie. A characteristic 
feature in the distribution of these animals is the fact that many species maybe 
found in a single restricted area. Thus, from a small pool not more than 30 feet 
across, in the Huron River at Ann Arbor, Mich., 14 species were taken, 6 species 
of Diurella and 8 of Rattulus. From East Harbor, Lake Erie, 20 species have been 
taken; this, however, is a rather extensive region. 
