STUDIES ON THE CILIATES FROM FRESH WATER MUSSELS

I. THE STRUCTURE AND NEUROMOTOR SYSTEM OF CONCHOPHTHIRIUS ANODONTÆ STEIN, C. CURTUS ENGL., AND C. MAGNA SP. NOV.

¹ From the College of the City of New York and the Marine Biological Laboratory, Woods Hole, Mass.

1. Three species of the genus Conchophthirius Stein are described: (1) C. anodontæ (Ehr.) Stein, from the mantle cavity, palps, and gills of Elliptio complanatus (Dill.); (2) C. curtus Engelmann, from the mantle cavity of Anodonta marginata Say, A. implicata Say, A. cataracta Say, Lampsilis radiata (Say), L. cariosa (Say), and Alasmidonta undulata (Say); and (3) C. magna sp. nov. from the mantle cavity of Elliptio complanatus (Dill.).

2. The chief structural differences between the three species are noted in the shape, size, and extent of the peristome, distribution and size of the endoplasmic granules, distribution and number of the ciliary rows, type of posterior dorsal suture, and shape, size, and number of nuclei.

3. The host specificity seems to be marked in the case of Conchophthirius magna, less marked in the other two species.

4. Cross infection undoubtedly takes place by swimming trophozoites.

5. A peculiar permanent slit through which the contractile vacuole discharges is described.

6. A well integrated and closely interconnected neuromotor system is described, consisting of external, internal, and peristomal fibrillar systems.

7. The neuromotor system is thought to be mainly conductile but some parts of it may possibly be contractile or even supportive.