AND PHYSIPLOQT OF THE TUNICATA. 317 



and outlets for ttie 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 pedunculate, 

 and are sometimes as large as the reproductive masses, from 

 which they chiefly differ in colour, being pale, somewhat pel- 

 lucid, 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 or level 

 surface for the support of the branchial sac, which otherwise 

 might sufier from the inequality produced by the genitalia. These 

 peculiar organs are found in all the OyntTiiadce that have been 

 examined, including Pelonaia, in all of which the reproductive 

 organs project boldly from the surface of the mantle. 



This arrangement of the reproductive organs also occurs in 

 Stycla mamillaris, and in two undescribed species of the genus, 

 recently obtained by the Eev. A. M. Norman at Gruernsey. In 

 Thylacium aggregatum the same disposition of these parts is also 

 found to exist. 



In Cynthia ovata, an undescribed species allied to C. squamu- 

 losa, we have a very remarkable modification of these organs. 

 Here there are only two generative masses — one placed immedi- 

 ately above the alimentary tube, the other within the intestinal 

 loop. They are elongated and fusiform, each being composed of 

 a double parallel series of squarish nodules, in which both ovary 

 and testis are combined. Each mass has its own proper oviduct, 

 and vas deferens, which pass forward, united, between the series 

 of nodules, and, extending a little way in advance of the organ, 

 open into the cloaca near to the anal orifice. 



But perhaps the most interesting variety of this apparatus 

 occurs in Pelonaia, in which there are two elongated tubular 

 ovaries, each being bent so as to form a wide loop ; they are at- 

 tached throughout to the mantle, and bulge out the lining mem- 

 brane ; one is on the right, the other on the left of the branchial 

 sac in front of th& greater portion of the alimentary tube. The 

 oviducts advance a short way beyond the ovaries, and open into 

 the cloaca, one on each side of the intestine, but considerably in 



