eo 
GEROULD: CAUDINA. 127 
cylindrical, but slightly tapering basal portion about three milli- 
meters in length, bearing upon its free extremity four conical or 
finger-like lobes or processes, each about one millimeter long. 
The latter are arranged in pairs; the two which arise on the side 
next the mouth may be called the axial pair; the others, situated 
upon the outer side of the extremity of the tentacle, we may 
designate as abaxial. The axial processes are slightly larger than 
the others, especially in the diameter of the base, and usually 
stretch forward, but with their apices turned away from each 
other; the more slender abaxial processes are frequently much 
curved outward and backward. These four lobes of the tentacles 
spread further in the radial than in a tangential direction. Pig- 
ment spots are not present on the tentacles of Caudina, though 
they have been described in connection with the closely related 
form, Haplodactyla. 
The statements made in regard to the number of tentacles in 
Caudina have been various. Gould (41) found eleven; Ayres 
(52) and Selenka (767) twelve; while Kingsley (’81) was of the 
opinion that the number varies from twelve to fifteen, as he 
found the latter number in counting the tentacles of several 
individuals. Pourtalés (51) had observed the number to be 
fifteen, each being, as he thought, divided into jive lobes; and 
Marenzeller (’82) upon examining numerous specimens found 
always fifteen tentacles, each having four lobes. Although I 
have counted the tentacles of scores of specimens, I have never 
found an individual with any other number than fifteen. Doubt- 
less the contracted condition of the specimens examined by the 
earlier investigators led them to overlook some of the tentacles. 
A prominent cone-shaped genital papilla is situated in the dorsal 
interradius 3 or 4 mm. behind the ring of tentacles. It was not 
to be found in the youngest individuals that I examined, which 
measured about 40 mm. in length. In the adult it is approximately 
2 mm. in length, and appears to be slightly larger in the male 
than in the female. 
There are five conical, transparent, anal papillae, one at the 
terminus of each radius. They are so minute as to be scarcely 
discernible without a lens, even in the living and expanded 
animal; they are about 0.2 mm. long. When the anus is open, 
these papillae lie stretched out, pointing directly backward; when 
the sphincter muscle contracts to close the anus, the papillae 
