Art. XXXV.—On a new Infusorian parasitic on Patella argentea.

By Prof. F. W. Hutton.

[Read before the Otago Institute, 8th October, 1878.]

Last month, while investigating the structure of Patella argentea, Quoy and Gaimard, I discovered numerous specimens of an infusorian attached to the branchiæ, of which the following is a description:—

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Body campanulate, naked, devoid of cilia, hyaline, highly contractile; sessile or subsessile; mouth surrounded by a spiral ring of rather coarse cilia, which are capable of being moved or held motionless at the will of the animal. Length, 1/500 inch. These little animals were attached to all parts of the branchiæ, and closed up suddenly, in the manner of Vorticella, when touched by any foreign body.

The absence of a carapace and of a stalk would appear to put this species into Trichoda, Ehr., but the disposition of the cilia round the mouth precludes this; and I am inclined to regard it as a Cothurnia, in which the lorica has become obsolete owing to its commensual habits. I therefore propose to call it Cothurnia patellæ.