178 GUY C. R0B80N 



seems to indicate a glandular nature. Very occasionally 

 spermatozoa were found in the receptaculum aggregated into 

 small subcircular clumps. 



(2) The Oviducal and Accessory Glands. 



Some excuse is perhaps required for cumbering nomenclature 

 with an additional obscurity. The appendage (Text-fig. 9) borne 

 upon the oviduct just below the receptaculum seminis 

 is called by Seibold the ' Anhangsdriisc des lleceptaculum 

 seminis ' and by Bregenzer the ' Eiwoissdriise '. The latter's 

 figures are not a sufficient indication whether structurally the 

 organs are similar in Bythinolla and P. ventrosa. 

 Devoting our attention to the latter we find the ' oviducal 

 gland ', as I prefer to call it, to be covered by a strongly- 

 developed muscular sheath with circular muscle fibres. In 

 general form it is an irregular-shaped gland with a short duct. 

 Internally it is very much folded. The cells of its inner layer 

 when not loaded with secretion are tall and narrow. The 

 nuclei are basal, and, when the cells are full of secretion, 

 they become driven close up against the basal membrane. 

 There are not very many accounts of the albumen gland in 

 Gastropoda. But from those available we can safely assume 

 that we are hardly warranted in calling this structure in 

 Paludestrina by that name. In Valvata (1) on the 

 one hand and Physa (22) on the other we see radically 

 different types of ' albumen gland ', and we can identify this 

 form with neither.^ Until more is known of this structure in 

 Gastropoda, and particularly in Prosobranchia, it is perhaps 

 better to avoid a too positive terminology. 



The vagina is a narrow slit-like cavity surrounded by 

 a large accessory glandular mass. It is thin- walled and cihated 

 internally. The glandular mass is very interesting but difficult 

 to interpret. Previous authors of recent work upon Taenioglossa 

 do not discuss it at any length, though Seibold pointed out that 

 differences of staining could be observed in it. Subject to cer- 

 tain qualifications, we may state that this mass is divisible most 



1 Cf. Slugocka's PI. iv, fig. 20. 



