48 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
Each of the white spots in the paired rows contains an inconspicuous, low 
rounded papilla (much less prominent than are the papillz of G. complanata, 
so far as my observations go). 
The median row of white spots is less well developed than are the paired 
rows ; in the four or five somites immediately anterior to the anus, it is com- 
monly replaced by a continuous, median, clear vitta, within which is seen a 
narrower band of the lemon-yellow reserve-food cells. 
Obviously the color pattern of this species resembles very closely that of G. fusca, 
although in a majority of characters the animal is more closely related to G. 
parasitica. 
6. Surrace, Rives, Somires, Eyes, Suckers. 
The surface of the body is rather rough, owing to the strong development in 
this species of the integumental sense-organs described by Bayer (98). It 
does not, however, bear conspicuous papille, as is the case with G. parasitica 
and the European G. complanata. The low, rounded papille which are 
found in the paired longitudinal rows of white spots are much smaller than 
the similarly placed papille of G. complanata. In this particular G. elegans 
seems to agree with G. concolor (see Apathy, 88, page 771). 
External rings, as a rule, rounded and distinct, less convex and not pointed as 
are those of G. complanata, sixty-eight in number, distributed as follows : — 
Somites 1—-Iv. uniannulate ; but the boundary between rings 1 and 2 is often 
inconspicuous (compare Figures 28, 29, 30), approaching the condition found 
in G. stagnalis, where somites I. and 11. form a single broad ring, which, how- 
ever, is sometimes divided by a shallow transverse furrow (Figures 3, 7). 
Somites v.-XXIV. triannulate, but the condition of somite v. is peculiar. Its 
anterior annulus (5, Plate 7, Figures 28-31) is commonly narrow and imper- 
fectly separated from the following (sensory) annulus (6). This case illus- 
trates well the initial step in reduction (or final step in elaboration, p. 33) 
of the triannulate somite. It represents an intermediate stage between the 
biannulate and triannulate condition of somite v. seen respectively in G. stag- 
nalis (Figure 7, Plate 3) and G. heteroclita (Figure 20, Plate 5). 
Somite xxv. is biannulate (Figure 28), but the furrow between its two annuli 
is often inconspicuous. Somites XXVI. and XXvH. are commonly uniannulate, 
though notched at the margin of the body, which fact shows that the final step 
in somite reduction (or initial step in somite growth) is not yet accomplished 
in the case of these somites. 
Eyes, six, in two parallel rows close together, in rings 3 and 4 (Figure 30). 
Sometimes the first pair of eyes lies partly in the posterior half of ring 2 
(Figure 29). The middle pair is the largest of the three ; the anterior pair, 
the smallest. The first two pairs are directed obliquely forward, the last pair 
obliquely backward; all are turned away from the median plane (Figures 29, 
30). From the relation of the eyes to the nerves connected with the metameric 
sensille (Figure 29), it is plain that the three pairs of eyes have been derived 
from the sensille of somites I., 111., and Iv. respectively. It is further evi- 
