GENUS FIROLA. 5 



the upper part of the nucleus, with which it communicates 

 by means of two apertures, one of which is simple and 

 the other double. 



Besides the above mentioned apertures in the nucle- 

 us, another oblong one is placed on the right side for the 

 passage of the oviduct; and another on the opposite side, 

 probably serving for excretio% Oviduct filiform, includ- 

 ing small remote globules. 



Vascular System. Composed of a heart, branchia, and 

 artery. The heart is placed between, and in contact, with 

 the branchia and artery. Branchia with from twelve to 

 sixteen perfoliated appendages. Artery extended from the 

 heart to its termination near the jaw, where it is surroun- 

 ded by four tubercles; in its course it passes through the 

 interstice of the double ganglion. A branch arises from 

 this principal artery, immediately before the last mention- 

 ed ganglion, furnishnig the dorsal fin with blood ^by 

 means of numerous smaller anastomosing branches, ex- 

 hibiting, m that fin, a reticulated appearance. 



Obs. In some species of this genus a lateral vermiform 

 organ is superadded; when this occurs, a second branch 

 arises from the principal artery to supply it with blood. 



Generative Organs. A vermiform organ is attached 

 to the left side of the body composed of •three parts; of 

 which, one is placed above, and seems intended to pro- 

 tect the others; the second is short, cylindrical, straight; 

 the third, elongated, vermicular, attached to the base of 

 the second. This is probably the generative part of the 

 male. The species furnished with an oviduct may be fe- 

 males, as this part is placed on the side opposite to that 

 of the vermiform organ, so as to facilitate the connection 

 between the sexes. 



