BARBADOS-ANTIGUA REPORTS 41 
segmented into a series of ganglia. In the unisexual annelids 
the reproductive organs are not well marked except during the 
breeding season. In the hermaphroditic forms, which have a 
direct development, there is a complicated system of repro- 
ductive organs. 
All annelids live in water or in moist places on the land or 
in the earth, the majority being marine. They swim mostly at 
night, and serve as food for fish and other animals. 
The class Chetopoda, or ‘‘bristle-worms,’’ comprises the Earth- 
worms, Fresh-Water Worms, and Marine Annelids. This class 
has bunches of bristles, or setz, on both sides of each segment 
of the body, which serve as organs of locomotion. The setz are 
of various shapes and colors. They are usually chitinous and 
vary with the genera. This class contains two subclasses: (1) 
the Polycheta, and (2) the Oligocheta. 
The subclass Polycheta, to which the annelids described in 
this paper belong, are the ‘‘many-bristled’’ worms. They are 
mostly marine, divided into two orders: (1) the Errantia, or 
free-swimming; (2) Sedentaria, or sedentary worms. Many 
Polycheta are beautifully colored—some in vivid reds, greens, 
blues, and yellows; others in the more sober shades of browns 
and grays. Some are iridescent; some are phosphorescent. 
The majority of the Polycheta have a cylindrical and very 
mobile body and have a considerable number of segments, 
definite in number in some groups and varying in others. The 
segments composing the trunk may be all alike or may con- 
stitute two more or less sharply marked regions, the thorax and 
the abdomen, which differ in the character or in the arrange- 
ment of the chete. The body-wall consists of a cuticle, an 
epidermis, muscular layers, and a layer of peritoneum. The 
cuticle is perforated in many places by the ducts of the uni- 
cellular glands of the epidermis, which consists of a single row 
of cells. In the tubicolous forms these glands secrete the 
material used in the construction of the tube. In addition, the 
epidermis frequently contains sensory cells, which are in many 
cases contained in sensory papille. The muscular part of the 
body wall consists of two layers. The outer layer has the fibres 
disposed circularly, while the inner one has them arranged 
longitudinally. The peritoneum is a single layer of cells. 
