On the egg capsules of _Crepidula plana_; also reported upon annelids
at Woods Hole.

Length 60 mu from disk to extremity of the peristomial disk.

[Illustration: Fig. 58.--_Lichnophora macfarlandi_.]

This form does not agree in all respects with Stevens's species, but
the agreement is so close in other respects that I believe it can be
safely identified as _L. macfarlandi_. The mode of life is different,
and the macronucleus is different, there being from 25 to 30
fragments in Stevens's form and only 5 or 6 in the present one. There
is, however, the same evidence of chain formation in both of them.
The length of the oral cilia in Stevens's form is 18 mu in fixed and
30 mu in living forms. In the Woods Hole form the cilia are not more
than half that length.

KEY TO THE MARINE GENERA OF VORTICELLIDAE.

Diagnostic characters: Attached or unattached forma of peritrichous
ciliates in which the adoral zone seen from above forms a right-wound
spiral. A secondary circlet of cilia around the posterior end may be
present either permanently or periodically.

1. Posterior ciliated girdle 3
permanent around an attaching disk

2. Posterior ciliated girdle, 4
temporary during motile stage

3. Body cylindrical:

(a) With ring of stiff bristles Genus _Cyclochaeta_
above the ciliated girdle

(b) Without accessory ring of Genus _Trichodina_
bristles; with velum

Body conical; general Genus _Trichodinopsis_
surface ciliated

4. No test and no stalk Genus _Scyphidia_

5. No test; with stalk containing 8
contractile thread

6. No test; with stalk but without Genus _Epistylis_
contractile thread

7. With a test; with or without Genus *_Cothurnia_
a stalk

8. Individuals solitary Genus *_Vorticella_

Individuals colonial; Genus *_Zoothamnium_
entire colony contractile

Individuals colonial; parts Genus _Carchesium_
only of the colony contractile

* Presence at Woods Hole indicated by asterisk.

Genus VORTICELLA (Linnaeus 1767) Ehr. '38

(Bell Animalcule Leeuwenhoek 1675; Ehrenberg '38; Dujardin '41; Stein
'51; Cl. & Lach. '58; Greeff '70; Buetschli '88; Kent '81; Stokes '88;
etc.)

Medium-sized ciliates of general bell-like form. They may be
colorless, or yellow and green through the presence of