554 



THE ANATOMY OF IXVERTEBRATED ANIMALS. 



are any cilia visible in them ; but the minute molecules which 

 float in the clear fluid which they contain are driven to and 

 fro, apparently by the contraction of the body. Inferiorly, 



Fig. Wl.—EcMnorhynchus.—k. Diagram exhibiting the relative position of the or- 

 gans : a, prohoscisJ ; 6, its stem ; c, anterior enlargement of the body ; /. neck or 

 constriction between the anterior enlargement ami the rest of ttie body, d ; e, 

 posterior '' funnel ; " </, meniscus: ^. superior oblique tubular bands; A", inferior 

 muscles of the proboscis : /, w, genitalia ; o, penis, or vulva. B. Lower extrem- 

 ity of the stem of the proboscis : a, ganglion ; 6, vascular space ; d, outer coat ; 

 c, inner wall ; e, tubular band, with the nerve ; A./, muscular bands ; g, suepen- 

 sorium of the genitalia. C. Part of the female genitalia: a, ovary ; b b, ducts 

 leading from ovary to uterus, spermiducts (?) ; c, open mouth of oviduct ; d, e, 

 uterus and vagina. 



the vessels all terminate in blind canals, disposed around the 

 margin of the posterior funnel. Internal to the vessel lies a 

 double layer of anastomosing muscular fibrils, the external of 

 which are circular, while the internal are longitudinal.^ The 

 cavity of the body is filled with a fluid, in which the ova, or 

 spermatozoa, float, and, at its anterior extremity, two elon- 

 gated oval bodies depend from the parietes, and hang freely in 

 it. These are the leinniscl ; they are traversed by vessels 

 continuous with those of the parietes. The axis of the pro- 

 boscis is continued downward into an elongated subcylindrical 

 stem, rounded below, which hangs down like a handle, into 

 the cavity of the body. The extremity of the stem is con- 

 nected by broad retractor muscles with the parietes, and 



* See^ for an account of the remarkable structure of these muscles, Schneider, 

 " Ueber den Bau der Acanthocephalen." (" Archiv fiir Anatomic," 1868.) 



