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ZOOLOGY 



SECT. 



some cases it is of even more complicated shape than in Triton, 

 owing to the branching of the lateral ridges. 



The excretory organs or kidneys of the Gastropoda are 

 dorsally placed glandular tubes or chambers, which communicate 

 internally with the pericardium, and open on the exterior, either 

 directly or through a duct the ureter. Both right and left kidneys 

 may be present, though unequal in size, the one situated to the 

 right of the anus being larger than that situated to the left ; or 



the former may alone 



& 



*tb 



^cilbgrl 



rec.sem 



be developed (Euthy- 

 neura). In a very 

 limited number of Gas- 

 tropoda the gonad 

 opens into the kidney. 

 The sexes are sepa- 

 rate in nearly all the 

 Streptoneura, united 

 in the Euthyneura. 

 Special gonoducts are 

 present, except in one 

 or two forms in which 

 the nephridia perform 

 that function. In the 

 unisexual forms the 

 reproductive appara- 

 tus is of a compara- 

 tively simple character, 

 consisting merely of a 

 racemose reproductive 

 organ, ovary or testis 

 as the case may be, 

 situated dorsally in the 

 visceral spiral, with 



FIG. 650. Reproductive organs of Helix, alb. gl. albumen- 



gland ; ds. dart-sac ; flag, flagellum of the penis ; herm. the ffOnoduct opening 

 gl. hermaphrodite gland or ovotestis ; herm. d. duct of 

 ovotestis ; muc. gl. mucous gland ; muc. gl. ap. apertures of 

 mucous glands into vestibule; ovid. oviducal part of the ,,;.>, fV, Q r>rl 

 common duct; ovid. ap. aperture of oviduct into vesti- rignt-nana 







iar |IOrwardS On tne 



bule; pen. penis; rec.~ sem. receptaculum seminis:; rec. m the male, a penis. 

 sem. ap. aperture of receptaculum seminis ; sp. d. sperm . .. . , f . 



duct ; sp. d'. spermiducal part of common duct. (After Which IS gTOOVCd longl- 



tudinaUy and non- 

 retractile. In the hermaphrodite forms, such as the Pulmonata 

 (Fig. 650), on the other hand, a considerable degree of complexity 

 is observable. There are an ovotestis or "^hermaphrodite gland " 

 (herm. gl., Fig. 651, A) some of the follicles of which produce 

 ova while others produce sperms, a convoluted " hermaphrodite 

 duct " (herm. 'd.), an albumen-gland, in which the albumen 

 of the relatively large eggs is formed, and sometimes a separate 

 oviduct and sperm-duct leading to a common genital opening ; 



