8 Mindeskrift for J. Steenstrup. XVI. 



the matter by which the eggs af ter extrusion loosely cohere, and corresponding to 

 the substance secreted in other Copepoda by the same part of the oviduct and 

 generally forming the "ovisacs". 



The distal end of the oviduct suddenly narrows into a very small pore opening 

 in the short vagina (Fig. 8, vg); the latter has a chitinous lining continuous with the 

 outer genital slit. Like this the vagina in transverse section is crescent-shaped, the 

 lateral wall or outer lip being strongly thickened, completely filling out the concavity 

 of the half-moon (Fig. 10); a strong muscle, serving as dilatator (dil, Fig. 10), is inserted 

 in the outer. lip. Just at the same spot where the oviduct opens in the vagina, 

 debouches also a narrow and short duet from a large, unpaired receptaculum seminis 

 (Fig. 8, rs). The latter is rounded or pear-shaped, with one pole imbedded between 

 the distal ends of the oviducts, the other projecting backwards into the genital segment; 

 its front end and the distal ends of the oviducts are surrounded by a mass of large 

 unicellular glands. In females with eggs in the oviduct the receptacle and its duets 

 always have been found filled with sperma; in young, unripe, females with empty 

 oviducts no sperma have been found, only a secretion, which seems not capable of 

 staining (produced by the unicellular glands ?). 



Thus in the Parasitic Copepod before us the following features may be pointed 

 out as unusual: 1) an unpaired receptaculum seminis with paired outlets, one to 

 each opening of the oviduct in the vagina; 2) absence of separate copulatory pores. 



Separate copulatory pores (or a single pore) are generally supposed to be typical 

 in Parasitic Copepoda, although their existence in many cases has not been proved 

 (GiESBRECHT 10, p. 190 — 191 throws some doubt upon their occurrence in certain 

 Asterocheridae). 



In Chordeuma the same slits, through which the eggs are laid, undoubtedly also 

 serve for copulation. I have examined the region in question very carefully, and 

 besides I have seen in some specimens spermatophores fastened into the genital (or 

 vaginal) slits (comp. PI. I fig. 13 spf). 



Alimentary canal. (PI. I Fig. 8). Behind the rounded upper lip (ul) the 

 narrow mouth-opening leads into a short, slit-like pharynx, lined with a continuation 

 of the outer cuticle. Muscles pass obliquely behind the root of the upper lip and 

 are inserted into the roof of the pharynx; a little further back other muscles are 

 inserted in its floor, taking their origin laterally and from behind; both sets aet as 

 diktators, antagonistically counteracted by the elasticity of the chitinous lining of the 

 pharynx; thus a sucking process may be brought about. The pharynx is continued into 

 a short and slender, cylindrical oesophagus (oe), passing through the central nervous 

 system (nv) and opening in the ventral side of the stomach (in). The epithehal wall 

 of the oesophagus consists of comparatively high cells, arranged in a single layer round 



