COE: TERRESTRIAL NEMERTEAN OF BERMUDA. 541 
mously developed and secrete a great amount of very tenacious 
mucus. Besides the mucus, the integument secretes great numbers 
of rod-like or flask like masses of a solid or semi-solid consistency, 
which give a finely punctate appearance to the body itself. 
The muscular system presents no marked peculiarities. The body 
parenchyma is rather voluminous, and there is much connective 
tissue among the cephalic glands in the head (fig. A). 
Cephalic glands. — An enormous development of the cephalic 
glands seems to be characteristic of all terrestrial nemerteans, and 
Geonemertes agricola forms no exception to the rule. In this species 
the cephalic glands occupy a great portion of the tissues of the 
head in front of the brain (fig. A) and extend far back into the 
esophageal region. As described below, they become very con¬ 
spicuous at an early period in the development of the embryo. In 
G. palaensis they open into a conspicuous terminal canal or frontal 
organ. In G. agricola and in G. graffi, according to Burger (’96), 
this frontal organ reaches a degree of development beyond that 
described for any other nemerteans, consisting of a conspicuous 
tube situated immediately above the rhynchodaeum and extending 
from the tip of the snout back nearly to the brain. It is lined 
throughout with large, columnar cells, a portion of which are ciliated 
and sensory in nature, as described by von Kennel (’78) for G. pal¬ 
aensis. The duct serves not only for the discharge of the vol¬ 
uminous secretions from the cephalic glands but also as a sense 
organ, and is thus homologous with the frontal organ of the Heter- 
onemertea. The frontal organ opens through the dorsal wall of 
the rhynchodaeal opening as a large tube having a diameter nearly 
half as great as that of the rhynchodaeum itself. The lateral walls 
of this tube are lined with slender columnar cells covered with fine 
cilia. The cells forming the dorsal wall of the tube, however, are 
much larger than the others, and are filled with a very clear cyto¬ 
plasm, while from their outer surface project fine strings of hard¬ 
ened secretion very much resembling large flagella. Farther back 
the ventral wall of the tube (fig. A) becomes lined with similar 
secretory cells, leaving only a narrow line of ciliated cells on the 
right and left walls of the tube. Back toward the brain region the 
tube passes into an almost solid mass of gland cells constituting the 
body of the cephalic glands. It then becomes of much smaller cali¬ 
ber and terminates posteriorly in the mass of cephalic glands imme¬ 
diately in front of the dorsal brain commissure. 
