576 MATNARD M. METCALF, 



Fig. 87, a figure of the visceral mass of 0. hithyus, from Herdman 

 after Moseley.) The ova are large and, in addition to the outer 

 follicle, show, in the larger eggs, an inner folHcle of many cells, 

 Ijdng within the contour of the ovum. The same individuals show 

 ova and spermatazoa, which, so far as one can judge from their 

 form, are mature. It is, of course, probable that the ova are cast 

 first, as in other Ascidians. In no case have I found larvae or 

 cleaving ova in my specimens. This may indicate that this species 

 does not carry its eggs after fertilization, or merely that these in- 

 dividuals were not quite ripe. I have copied Moseley's figure of 

 the visceral mass of 0. hithyus^ showing the gonads. 



The neural gland and ciliated funnel have already been described 

 in Section I, page 549 (cf. Plate 40, Figs. 86 and 88). It proved 

 wholly impossible to demonstrate by dissection even the presence of 

 the brain and the neural gland. The tissues were all so soft that 

 it was impossible to pick away the overlying membrane and muscles 

 without tearing the ganglion and gland beyond recognition. With 

 great difficulty, because of the grit in the alimentary canal, I suc- 

 ceeded in getting one complete series of sections of one whole 

 visceral mass and a second series of sections of a strip cut from 

 the dorsal surface of the visceral mass. From these sections one 

 can readily see that the ganglion has the character usual in the 

 Tunicates, with a fibrous medulla and a cellular cortex (Fig. 88 gg). 

 Two very large nerves protrude anteriorly from the ganglion and a 

 single nerve, the rapheal nerve, pushes, back from the brain, along 

 the mid-dorsal line of the visceral mass (Fig. 86). As a number of 

 the sections are torn, I am unable to make an accurate recon- 

 struction of the brain and neural gland, but I give in Fig. 86 the 

 impression of the superficial appearance of these organs, which I 

 have gained from a study of the sections. I do not think it can be 

 far wTong as regards the size, shape or mutual relations of these 

 organs. The slight degree of asymmetry in the position of the 

 rapheal nerve is indicated in the sections by the fact that it lies 

 nearer to the right strand of the rapheal muscle than to the left. 



One other feature of special interest in Octacnemus paiagoniensis^ 

 as compared with 0. hithyus, is the fact that the individuals are 

 bound together into a colony, by a stolon running from near the 

 base of the body of one animal to its neighbors in front and behind, 

 in such a way as to unite them into a linear series of individuals 

 placed belly to back (Fig. 81). In two cases, I find two individuals 



