490 KEPORT OF COMMISSIONER OF FISH AND FISHERIES. [38] 



Order ACANTHOCEPHALA Rudolphi. 



Echinorhynchus Zoega. 

 EchinorhynclMS agilis Rudolphi. 



[Plate V, Figs. 1-6.] 



E. agilis Rudolphi, Synopsis, 67 and 316. Westrumb, Acanthoceph., 17, tab. 

 i, 1. Breraser, Icon. Helminth., tab. vi, 9-10. Dujardiu, Hist. Nat. des 

 Helminth., 535. Diesing, Syst. Helminth., ii, 35, and Revis. der Rhyngod., 

 746. Molin, in Sitzungsb. d. Kais. Akad. d. Wissensch., xxs, 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 tbe 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 threelobed, 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 XCW to 12 mm in length ; males 4.6 Ilim to G.44 mm . 



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 JEJ. 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, e. </., one specimen had four on the concave side and two on the 



