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VI. — Note on a Tapeworm from Echidna (T tenia Echidnas sp. n.). 
By D’Arcy W. Thompson. 
{Read 19 th April, 1893.) 
Plate Y. 
Some few months ago Prof. Jeffrey Bell entrusted me with a small 
number of Tapeworms from the intestine of Echidna hystrix, pre- 
served and brought home by Prof. T. P. Anderson Stuart, of Sydney, 
N.S. W. So far as I am aware, the cestode parasites of the Monotremata 
are quite unknown, and the new species is therefore interesting from 
its habitat, though it shows no very remarkable points of structure. 
Having been fixed in chromic acid, the worms are very much con- 
tracted. The longest specimens measure about 5 cm., and contain, 
besides the head, about 200 proglottides. The ripest proglottides are 
about • 7 mm. long ; the worm is about 4 mm. broad from side to 
side, and about 1 mm. dorso-ventrally. 
Taenia Echidnas belongs to the unarmed or hookless section of 
the genus. The head is exceedingly small, short and low, and is sur- 
rounded by a thick, broad ridge or fold, little broader than the 
neck ; viewed from above, the head is oval in outline. Tiie proboscis 
is a low conical eminence, rising gradually from within the outer 
boundary ridge. Between the ridge and the eminence of the proboscis 
are the four suckers, visible in the preserved specimens as so many 
small slits, within which the suckers are concealed as deep invaginated 
pouches. The neck is short, broad, and ill-defined, little narrower 
than the head in front, and reaching within the space of a very few 
proglottides to the lull breadth of the body. The generative aper- 
tures open on the margins of the proglottides, in irregular alternation. 
From three to six open consecutively on the one side, to be succeeded 
by about as many more opening on the other. The penis is long and 
smooth, the genital cloaca deep and well developed. In transverse 
sections the longitudinal nerve-cord, the inner and outer water-vessels, 
and the commissural water-vessel in the posterior end of each pro- 
glottis were easily seen. The small number of available specimens 
did not warrant a further study of the internal structure, nor did any 
features of discrepancy from the normal type of the genus appear to 
render it necessary. 
EXPLANATION OF PLATE V. 
Fig. I . — Txnia Eclddnx sp. n., nat. size. 
„ 2, 3. — The head and anterior portion of the worm, x 6. 
„ 4. — The head of another specimen, x 6. 
„ 5. — The head, rendered transparent with oil of cloves, to show the suckers 
X 20. 
„ 6. — A portion of the body of the worm : x position of genital apertures, x 10. 
„ 7. — Ditto, in marginal view, showing the exserted penes, x 10. 
„ 8. — A transverse section through the genital cloaca, g. cl. ; p. sh., sheath of the 
penis; pr. p., protractor penis; od., oviduct; n. c., nerve-cord, x 110. 
„ 9. —A transverse section, to show n. c., nerve-cord ; o. w. v., outer longitudinal 
water-vascular canal ; i. w. v., inner ditto, x 110. 
