ANATOMY AND PHYSIOLOGY. 2<> 



double; and in A. venosa the male vesicles are exceedingly 

 minute and are very numerous. In Corella parallelogramma 

 the geiiitalia have much the same disposition; the ovary, 

 however, which is branched and tabulated, is spread out >n\ 

 both sides of the alimentary tube as is likewise the male 

 organ, the secerning vesicles of which are clustered into 

 dendritic systems. 



These organs, however, are modified to a much greater 

 extent in the Cijntldad& in many of which it is not easy to 

 determine the parts, on account of their intimate union ; and 

 very careful examination is requisite in these cases. In Styela 

 tul>eruKa the so-called ovaries are very numerous, and are 

 studded over the inner surface of the mantle on both the 

 right and left side of the body, causing the lining membrane 

 to bulge out. When fully developed they form protuberant, 

 ovate, orange-coloured masses, each having at the attenuated 

 extremity a projecting nipple-like papilla. This is the oviduct, 

 leading out of the ovarian mass or ovigerous sac ; for each 

 mass is really a sac in the walls of which the ova are de- 

 veloped. And firmly attached around the base of these sacs 

 is a series of pale oval vesicles which are sunk in. the sub- 

 stance of the mantle, and which form for each sac a sort of 

 cup within which it rests. These vesicles are the male se- 

 creting organs, and their ducts, extremely delicate tubes, 

 pass upwards over the surface of the sac, and go to join, on 

 the median line, a slender vas r/r/'m -//.v, which, passing 

 forward, terminates at the extremity of the short nipple- 

 like oviduct above described. Thus it is seen that the 

 so-called ovarian mass is a compound organ, combining both 

 the male and female parts, each with its proper secreting 

 organ and duct. There are therefore as many oviducts and 

 outlets for the male secretion as there are compound repro- 

 ductive masses ; and the eggs must be shed everywhere into the 

 space between the branchial sac and the wall of the respiratory 

 chamber, and afterwards carried by the atrial currents to the 

 cloaca, and so pass out, as usual, by the excurrent tube. 



These reproductive masses should not be confounded with 

 other very similarly-formed bodies that everywhere stud the 

 mantle, and fill up, to a considerable extent, the spaces between 

 the former. These latter bodies are most frequently pedun- 

 culate, and are sometimes as large as the reproductive masses, 

 from which they chiefly differ in colour, being pale, somewhat 

 pellucid, and almost homogeneous in structure. They do not 

 seem to have any high functional import, their office apparently 

 being to form, along with the generative bodies, a sort of pad 



