300 Introduction to Animal Morphology. 



arrangements of the ducts are liable to vary,* and to 

 them may be appended receptacula seminisf and 

 nervous glands, with clear and opaque cells. + The 

 penis is protrusible like a glove-finger, sometimes spi- 

 rally rolled when not in use. In Pulmonates there is 

 always a multilobar hermaphrodite gland, often with 

 cascal processes (Limnsea), with an often tortuous her- 

 maphrodite duct ending in a double tract, the female 

 product escaping by an oviduct into a dilated uterus, 

 below which is a pouch-like rcceptaculuiii scuiiiiis and 

 an albumen gland ; the female organ ends in a va- 

 gina. The male duct begins as a ciliated groove, 



* The varieties are as follows : — A. Genital gland branched, diffused in 

 the body. 



I. Male and female glands separate, with a branched prostate, and 

 both ducts far forward = Elysia (Placobranchiata) [Pagenstecher 

 describes Elysia as having a hermaphrodite gland]. 

 II. Male and female glands not separate, but distinguishable ; pros- 

 tate diffused ; vagina far back= Pontohmax (Abranchiata). 



Male and female glands not separate, but distinguishable ; pros- 

 tate unkno\vn, all sex ducts united =Tergipes (Gymnobrancliiata). 



III. Male and female glands united ; prostate simple ; follicles sepa- 

 rate = Rhodope (Abranchiata). 



Male and female glands united, prostate simple ; follicles her- 

 maphrodite = PhyUirhoe (Abranchiata). 

 B. Genital gland consolidated behind the liver ; prostate simple. 



IV. Male and female ducts at first united, then separate, ovarial, 

 vaginal and seminal openings close in a cloaca = Fiona, Facelina, 

 Tethys, Doris, Dendronotus, Pleurobranchus, Pleurobranch^a. 



V. Male and female ducts united for a long extent, with no inner 

 canal to the penis ; genital openings separate, but close together 

 = Pleurophyllidia, Umbrella. 



Male and female ducts united for a long extent, with no inner 

 canal to the penis ; penis far in front of the vagina, with a cihated 

 canal = Aplysia, Doridium, Gasteropteron, Phihne. 

 t Described as the Swammerdamian vesicle. 

 X Umbrella has a csecal pouch between the vagina and uterus. 



