STUDIES ON 'THE DIGENETIC ''REMATODES. 459 
? Fellodistomum incisum (Rud.) Stafford, “Trematodes 
from Canadian Fishes,” in ‘ Zool. Anzeig.,’ xxvii (1904), 
p- 486. 
This species has already been recorded from the east coast 
of Britain by Miss Lebour, It is a remarkably frequent 
parasite of the cat-fish (Anarrhichas lupus) being met 
with in almost every specimen, young and old. Its habitat 
is exclusively the gall-bladder. Fifty examples, at least, can 
usually be obtained from one host. 
On the question of the identity of this species with two 
species found by Rathke! in Anarrhichas lupus and named 
by Rudolphi,? several authors have ventured an opinion. 
Van Benedin® considered D. fellis Olss. synonymous with 
D. incisum Rud. Stossich also evidently considered the 
two species identical, but retained Olsson’s name. Jacoby 
repudiated the possibility of such identity. Stafford, leaving 
his reasons unexplained, adopts Rudolphi’s name, and makes 
Dist. incisum Rud. the type of his genus Fellodistomum. 
How he identifies the species which he describes with 
Rudolphi’s species is to me not very apparent. It has little 
in common with Rudolphi’s description. 
As regards D.incisum Rud. my opinion coincides with 
that of Jacoby. By no legitimate means can the form 
figured by Rathke and described by Rudolphi be made to 
agree with D. fellis Olsson. On the other hand, Rathke’s 
second species, which Rudolphi* provisionally named Dist. 
anarrhiche lupi, bears an undeniable resemblance to 
Dist. fellis.» The only description of this form, beyond its 
habitat and size, is contained in Rathke’s words ‘ corpore 
elongato carneo, apertura dorsali rotunda annulo luteo 
' «Dansk. Naturhist-Selsk. Skrivt.,’ v (1799), p. 70, pl. ii, fig. 3, 
2 *Entoz. Hist.,’ ii (1), p. 361. 
3 *Mém. Acad. Roy. Belg.,’ xxxviii (1870), p. 48. 
4 *Entoz. Hist.,’ ii (1), p. 435. 
° Olsson undoubtedly recognised this, for he marks D. anarrhichex 
lupi as doubtfully identical with D. fellis. At the same time he 
completely ignores such a possibility in the case of D. incisum Rud. 
