38 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
median line of the dorsal groove of the body are two narrow, parallel stripes 
of an intense reddish brown color, which are in contact with one another in 
the median line. In the ventral median groove of the body are two parallel 
stripes of about the same color as those in the dorsal groove, but with this 
difference, that they are separated from one another by a distance about equal 
to the diameter of either of the lines, and that the two ventral stripes are of 
not quite the same diameter. Both the dorsal and ventral stripes of color 
disappear near the two ends of the body. 
Dimensions. Length, 295 mm.; greatest diameter, 1.5 mm. 
This species is sharply distinguished from all other species of the genus 
known to me by the peculiar form of the posterior end, and by the colored 
stripes lying within the median grooves of the body. Unfortunately the 
locality is not given for the specimen. I have named it in honor of the pioneer 
student of the American Gordiacea, Joseph Leidy. 
3. G. agassizi, n. sp. 
Figs. 63-66, Plate 9. 
(Type, 1 male : Harvard collection no. 296, Sandwich Isl.) 
Form. Body much flattened dorso-ventrally, without well marked median 
grooves; the body is flattened in such a way that the dorsal side is rounded, 
the ventral side concave, so that a cross section would show the body to be 
somewhat sickle-shaped. Head end likewise dorso-ventrally flattened. The 
particular characteristic of this species, however, is that the broad plane of the 
neck does not coincide with the broad plane of the head, but is nearly vertical 
to it (Fig. 63). Thus the flattening of the head and of the body lies in approx- 
imately the same plane, while the neck region (for a distance of about .9 mm.) 
is twisted around through an angle of nearly 180 degrees, and hence the broad 
plane of the neck is nearly vertical to that of the head and to that of the body. 
Hence in viewing the head end either from the dorsal (Fig. 63) or the ventral 
aspect, the neck appears like a short slender thread, This relation has prob- 
ably been produced by a torsion of the neck region through an angle of nearly 
180 degrees. The outline of the head, viewed from the flattened surface, has 
somewhat the shape of an unbarbed arrow-head, broadest posteriorly and with 
rounded tip ; the mouth opening is large, transversely elongated, and situated 
at the termino-ventral margin of the head. The neck inserts itself along an 
elevated ridge which cireumscribes the posterior portion of the head. On the 
dorsal surface of the head (Fig. 63), to each side of the median line, are found 
just behind this elevated ridge a number of small ridges which are parallel to 
one another (i. e. those on the same side of the ridge are parallel), and these 
are obliquely disposed to the large ridge. These relations are difficult to 
describe, but may be understood by comparing the figure. 
The tail lobes (Figs. 65, 66) are bent ventrad, nearly at right angles to the 
posterior end of the body region proper. Hach tail lobe is much flattened 
laterally, and is very short; it is somewhat rounded on the lateral, and corre- 
