ON TEMNOCEPHALA. 297 



is discharged the secretion of the unicellular glands already 

 mentioned as apparently forming a part of the system of sub- 

 cutaneous glands. The secretion consists of or contains little 

 spherical, highly refracting bodies, which stain darkly with 

 hematoxylin ; probably the foreign particles found in the re- 

 ceptaculum seminis with the spermatozoa are the products of 

 this secretion. 



The female organs consist of receptaculum seminis, or 

 single ovary, oviduct, uterus, vitelline, and uterine glands, 

 together with certain of the subcutaneous glands opening 

 around the sexual orifice, which probably secrete the viscid 

 matter by means of which the eggs adhere together. 



The receptaculum seminis (PL XX, fig. 6, re., and PI. 



XXI, fig. 8, rec. sem.) is a large rounded sac which lies in 

 the middle line in a deep bay of the posterior wall of the in- 

 testine. Its walls are formed of a granular protoplasmic 

 matter, without differentiation, into cells, but with large nuclei 

 here and there. External to this is a thin layer of muscular 

 fibres. In all the specimens examined the cavity of the sac 

 was found to be full of spermatozoa, with frequently small 

 particles of amorphous matter, probably derived from the 

 accessory glands of the male organs. 



Opening out of the left-hand corner of the receptaculum 

 seminis is the oviduct (o. d. in PI. XX, fig. 6; PI. XXI, fig. 

 8; and PI. XXII, fig. 12), a rather narrow, curved tube which 

 opens below into the uterus. The wall of the oviduct (PI. 



XXII, fig. 12) consists of an external circular and an internal 

 longitudinal layer of muscular fibres, and is devoid of epithe- 

 lium, but is lined internally with a homogeneous layer of some 

 delicate non-nucleated material, which is not readily acted on 

 by staining agents. Into its lumen open the ducts of a few 

 of the shell-glands. 



The wall of the uterus (PI. XXI, fig. 8) resembles that of 

 the oviduct in structure ; but the muscular layer is thicker, 

 and the fibres cross one another in all directions. Most of the 

 shell-glands open into the uterus. Each shell-gland (s. gl.) is a 

 single, irregularly. shaped cell of very large size, with a large 



