40 BRITISH TUNICATA. 



after advancing to near the top of the sac, it turns 

 downwards, and in a great measure passes in front of 

 the generative mass. 



The reproductive organs are in two masses, which 

 are placed, one at each side of the body, adhering to 

 the mantle and bulging out the lining membrane. 

 They are, in M. conchilega, of an irregular oval form 

 and somewhat arched, each being composed of both 

 male and female elements. That on the right side lies 

 in contact with and directly above the rectal portion of 

 the intestine, the loop being below and behind it. 

 The ovigerous portion of the organ forms the upper 

 border of the mass, and is an elongated, lobed sac, 

 with the anterior or ventral end produced into a short, 

 constricted duct, which opens into the atrium at the 

 right side of, and a little way above, the anus. The 

 testis is composed of a vast number of branched 

 vesicles or csecal tubes, crowded together and some- 

 times assuming a dendritic appearance ; the mass thus 

 constituted is elongated and tabulated, and forms the 

 lower margin of the ovary, in close contact with the 

 intestine. There are four or five long, nipple-like 

 sperm-outlets or ducts, rising up in a line, at a little 

 distance from each other, on the surface of the testis, 

 towards its lower border. These convey the male 

 secretion into the atrial space by the side of the 

 branchial sac. 



The reproductive mass on the left side is similar to 

 that on the right ; it is, however, less regular in f 01*111, 

 and the male and female portions have in great 

 measure changed places ; for, on this side, the male 

 secreting vesicles occupy for the most part the upper 

 border of the organ, the female the lower. The whole 

 mass lies immediately above the curious, cylindrical 

 organ in connection with the heart. The oviduct 

 opens into the left-hand side of the atrium a little 

 above the anus. The sperm-outlets are as in the right- 

 hand mass. 



In M. simplex and M. inconspicua these organs are 



