Helminth Fauna of the Dry Tortugas. 177 
4. Lutianus griseus. 
July 5.—One small larva from this host, while much smaller than usual 
for this species, agrees so closely with it in the arrangement of the hooks 
that it also is recorded here. 
Another like it was collected on July Io. 
Dimensions of living specimen, slightly compressed, in millimeters: 
Length 3.64; head, length 0.49, breadth 0.63; neck, length 1.96, breadth, 
anterior, 0.35; bulbs, length 0.51, breadth 0.14; proboscis, length, estimated, 
1.40, diameter, exclusive of hooks, 0.04; length of largest hooks, about 0.021. 
18. Rhynchobothrium simile sp. nov. 
(Plate 5, figs. 30-37, and plate 6, fig. 38.) 
This tetrarhynch belongs to the group of comparatively large forms, 
represented by R. imparispine and R. speciosum, to which it bears a close 
resemblance. It resembles the latter in the general habit of the scolex and 
neck, but is more like the former in the character of the hooks. Indeed, 
at the time of collecting it was thought to belong to that species, and it was 
not until the hooks were examined critically that the great difference be- 
tween them and those of R. imparispine was revealed. The general charac- 
ter and arrangement of the hooks may be seen in the figures. 
Bothria, in alcoholic specimens, about as broad as long, emarginate on 
the posterior border, with margins raised so as to make the face a deep 
cup; in marginal view distinct from each other, the posterior ends flaring 
slightly. Head in both marginal and lateral views wider than neck. The 
bothria are attached on those sides of the head which correspond to the flat 
surfaces of the strobile. Contractile bulbs rather long and slender, the 
retractor muscle of the proboscides being attached at the posterior ends of 
the bulbs. 
The first segments begin near the base of the neck, at first as faint trans- 
verse lines, then as distinct segments much broader than long, lengthening 
posteriorly, soon becoming squarish, and ultimately longer than broad. 
The entire strobile is linear and the segments squarish. In a typical speci- 
men, measuring 50 mm. in length, the last segment was 2 mm. in length 
and 1.5 mm. in breadth. The average length of the last four segments was 
a little less than 2 mm. 
The genital cloaca is at about the posterior third, and is a shallow notch 
with abrupt sides. In glycerin the segments show longitudinal striz like 
those noted in R. imparispine (Report U. S. Fish Com. for 1887, pp. 840- 
843, plate xu, figs. 6-9). 
The proboscides are long and beset with hooks of many different pat- 
terns, the longest of which measures as much as 0.2 mm. 
Dimensions of a specimen mounted in balsam, in millimeters: Length 
of head and neck 6; bothria, length 1.20, breadth 1.00; bulbs, length 2.5, 
