HEEMAPHRODITISM IN MOLLUSCA. 25 



sented both ova and spermatozoa in the genital gland at the 

 same time. Each specimen had the glands either full of the 

 products of one sex exclusively (fig. 8), or else almost empty 



Nevertheless it is impossible to suppose that they repre- 

 sented the successive stages, male and female, of an hermaphro- 

 dite condition : in the first place, because the individuals with 

 male glands were no smaller than those with female glands, — 

 there were female specimens smaller than the males, and males 

 and females of every size ; in the second place, because the 

 appearance and conformation of the genital glands difiPers con- 

 siderably according to the nature of the contents, as in Lamel- 

 libranchs of different sexes. The glands with spermatozoa are 

 formed of ramifications having an appreciably constant dia- 

 meter (fig. 4, ii) ; the glands with ova are more lobulated, and 

 so present a distinct appearance, which shows that O. cochlear 

 is dioecious, like O. virginica and O. angulata. 



I will add a word here upon the genital apertures of 

 O. cochlear. They are asymmetrical, that of the left 

 being the more anterior (fig. 6, ix), considerably in front of 

 the adductor muscle. The"fente uro-genitale," discovered 

 by Hoek in O. edulis (17) (where the genital gland opens 

 into the urinary slit), has not in this species the simple 

 appearance which it presents in O. edulis. The genital and 

 renal orifices, although adjacent, are quite distinct; the genital 

 is more anterior than the renal, less distant from the median 

 plane (fig. 7, v), and directed outwards, whilst the renal 

 aperture is directed towards the axis (fig. 7, x). 



(2) Cardium oblongum. 



Lacaze-Duthiers discovered the hermaphroditism of a species 

 of this genus, C. norvegicum, from the Atlantic. I have 

 further observed this condition in a Mediterranean species, 

 C. oblongum, which is grouped with C. norvegicum in a 

 special division or sub-genus (Lsevicardium). 



In Cardum oblongum the different acini are each of one 

 sex, either male or female ; but the acini of the same sex are 



