490 | REPORT OF COMMISSIONER OF FISH AND FISHERIES. [38] 
ORDER ACANTHOCEPHALA Rudolphi. 
ECHINORHYNCHUS Zoega. 
Echinorhynchus agilis Rudolphi. 
[Plate V, Figs. 1-6.] 
L, agilis Rudolphi, Synopsis, 67 and 316. Westrumb, Acanthoceph., 17, tab. 
i, 1. Bremser, Icon. Helminth., tab. vi, 9-10. Dujardin, Hist. Nat. des 
Helminth., 535. Diesing, Syst. Helminth., ii, 35, and Revis. der Rhyngod., 
746, Molin, in Sitzungsb. d. Kais. Akad. d. Wissensch., xxx, 142. 
Color white. Proboscis clavate, very short, nearly globose, armed 
with three, sometimes apparently only two, series of hooks, about six 
in each series. Hooks in front row three or four times as long as those 
in second and third rows, each with a long, flat basal support.. Front 
hooks sharply recurved, with recurved part long, pointed, and often 
slightly concave on the outer edge. Remaining hooks very small, slen- 
der, slightly bent, sometimes standing out nearly at right angles to the 
axis of the proboscis, when the latter is exserted. Anterior part of the 
body slightly contracted and capable of introversion along with the 
proboscis, thus forming a short, transversely plicate neck. Body arcu- 
ate, club-shaped, cylindrical, transversely rugose, widest a little in 
front of the anterior third, narrowing rapidly in front and diminishing 
uniformly but very gradually to the posterior end, which is truncate. 
Proboscis sheath rather short, manubriform; proboscis and sheath often 
found retracted by an invagination of the anterior body wall. Lemnisci 
usually long, slender, attenuate posteriorly, longer proportionally in 
male than in female. Testes three-lobed, followed by an oval opaque 
mass. Male genitalia posteriorly continued into a cup-shaped copu- 
latory organ, which is capable of eversion and inversion. 
Females 9"™ to 12™™ in length; males 4.6™™ to 6.44™™. 
When subjected to the action of the compressor a series of oval and 
circular cavities becomes visible in the inner coat of the body wall. 
These are evidently the channels of the vascular system seen in section. 
At intervals, however, there are large circular spaces in this vascular 
layer clearly defined by a circular thickened ring of connective tissue. 
These become so much enlarged in some as to be visible with a com- 
paratively low magnifying power, and give rise to small mammillary 
elevations in the superficial layer of the body wall. These are evidently 
the “pores” or “ orbicular disks” given as specific characters of #. tu- 
berosus (Dujardin, Nat. Hist. Helminth., p. 538). They are described as 
usually numbering five or six on the convex side‘and a single one on 
the concave side. In the specimens which I have examined there does 
not appear to be either this regularity or proportion in their arrange- 
ment, ¢. g., one specimen had four on the concave side and two on the 
