1892.] , Zoology. 1039 
whether any two of them are identical with each other or similar to 
Linton’s species. At any rate, the name is clearly preoccupied, and it 
is inconceivable how Linton could give the same name to a fourth 
species which he describes as new, 
7. Distomum flexum sp. n. from Oedemia americana. 
8. Dibothrium cordiceps Leidy. Larus californicus as a new host. 
9. D. exile sp. n., from L. californicus. 
Episton gen. nov. Diagnosis: “Anterior end of body (head) lamel- 
late, more or less crispate, deflected. Body proper, tæniæ form, seg- 
mented, segments not distinct. Reproductive apertures lateral (?).” 
Epision is, without doubt, identical with Tenia malleus Goeze, 1782. 
Since Goeze’s time, the parasite has been mentioned by Zeder, 1800; 
Frölich, 1802; Rudolphi, 1808, 1810, and 1819; Bremser, 1824; 
Creplin, 1839 ; Dujardin, 1845; Schlotthauber, 1860; Krabbe, 1869; 
Krefft, 1871. It has been figured by four of these authors. 
10. E. plicatus sp. n., from Oedemia americana. 
11. Tenia sp. fragments from Larus sp. and Colymbus sp. 
12. Tenia porosa R. from L. californicus. 
13. T. filum Goeze, from L. californicus. 
14. T. macrocantha sp. n., from Oe. americana. 
15. T. compressa sp. n., from Fuligula vallisneria. 
It must be confessed that Linton’s paper is a disappointment, and far 
inferior to his papers on the parasites of fish. Although he has given 
good descriptions of the external appearance of the parasites, measure- 
ments, etc., yet he has said almost nothing about the internal organs. 
In fact, he has described as s si apoia of Dibothrium, a form in 
which no genital d; while in his supposed new genus 
he cannot even give 2 the position of the genital pores with certainty, and 
tells us practically nothing in regard to the genital glands. In the case 
of T. filum, T. macrocantha and T. compressa, an attempt is made to 
figure the genital organs, but the figures are very poor, too small and 
do not contain enough detail. We are told nothing of the number of 
testicles or of the topographical relations of the various organs. 
The time has now passed when an helminthologist is justified in cre- 
ating new species or new genera of tape-worms on external form 
alone, especially when only one or two specimens are at his disposal. 
If specimens of Linton’s species were sent to me for determination, 
and I knew the hosts from which they came, I might be able to deter- 
mine the various forms; but I must confess that if the parasites alone 
were sent, with no statement as to where they came from, it would be 
practically impossible to recognize the species. Even with the forms 
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