880 DR. F. E. BEDDARD ON 
much further into the ripe proglottid than it does in Otiditenia. 
I have re-examined my preparations of Otiditenia, and find that 
my report upon its structure as regards the above points in which 
it differs from Sphyroncotenia is correct as to fact. 
But I find that I have missed one point of resemblance to 
Sphyroncotenia, and through it, to the subfamily Idiogenine 
of the Davaineide, This has, of course, an important bearing 
upon the classification and position of Otiditenia in the system. 
While admitting its resemblances to Davainea, and by inference 
to the Davaineide, I was inclined to place Otiditenia nearer to 
Choanotenia and its allies. This was, undoubtedly, due to my 
not having seen a paruterine organ, though its presumed 
absence was not made use of in the generic definition *, or in the 
résumé of the most noteworthy characters of the genus following 
the definition. Nor, indeed, do the nearly mature proglottids 
show any structure exactly resembling the paruterine organ of 
Idiogenes, Stilesia, Anonchotenia, Sphyroncotenia, Rhabdometra, 
and other forms as figured by various zoologists im memoirs 
known to me. In all of these instances, and in others, the 
paruterine organ is represented as a structure of fibrous appear- 
ance and of limited size, formed apparently from a metamorphosis 
of the medullary ground-tissue in the immediate neighbourhood 
of the uterus or from the walls of the uterus itself. This latter 
origin is asserted by Gough t for Avitellina centripunctata, while 
Ransom’s figure t of a “‘ mature segment becoming gravid” of 
Rhabdometra similis may be interpreted ina like manner. But 
whatever be the origin of these paruterine organs §—and both 
Fuhrmann and Gough believe them to be not strictly homologous 
through the series—they would appear to have been described as 
small bodies lying in, and possibly derived from, but ultimately 
independent of, the medullary parenchyma. 
In Otiditenia, however, the more mature segments show an 
alteration in the medullary parenchyma to which J have referred, 
and which I have figured in my memoir upon that genus || 
This alteration affects the whole of the medullary parenchyma as 
seen in that section 4] of a nearly mature proglottid. It is visible 
up to the circular muscular layer which forms the line of 
demarcation between the cortex and the medulla, except where 
it is separated therefrom by the ventral water-vascular tube as is 
also shown in my figure. The dorsal smaller water-vascular vessel 
lies well within the core of medullary parenchyma, as is also 
shown in the figure referred to. There is not, therefore, to be 
* Loc. cit. p. 220. 
+ “A Monograph of the Tape-Worms of the Subfamily Avitellining.” Quart. 
Journ. Micr. Sci. lvi. pt. 2, 1911, p. 375. 
+ “The Teenioid Cestodes of N. American Dirds.” Bull. U.S. Nat. Mus. No. 69, 
1909, fig. 23, p. 31. 
§ I do not refer here to the multiple paruterine organs of Davainea, Zschokkeella, 
etc. 
\| Loe. cit. p. 218, text-figs. 23, 24, 26, 29. 
§| Loe. cit. fig. 29, p. 212) 
ae ae 
