|:;-j "TERRA NOVA" EXPEDITION. 



al organs. They then become separated by muscular tissue from the ventral 

 portion of the "U" (PI. II, fig. 4, V.B.S.), just as iu L. n-ru. : i<itiix, so that there are 

 fur a short distance three apparently distinct spaces. Further back, the system of 

 intercommunicating vessels is not nearly so elaborately developed as in the former 

 species; the blood-spaces round the gut are by no means so distinct or so numerous, 

 the most conspicuous being a pair of longitudinal vessels situated to right and left of 

 the prosboscis-sheath, dorsal to the gut (PL II, figs. 2 and 5, B.S.). A few smaller 

 and more irregular vessels can be seen laterally and ventrally. 



Si'iiNi'-nri/tuix mill Nervoux System. There is a minute " frontal organ " at the 

 tip of the snout, and the head is very abundantly supplied with gland-cells, some 

 of which are probably connected with it. 



The cephalic slits are very deep and straight-sided. There is very little expansion 

 at the bottom of the furrows, which communicate with the 1 train only at their hinder 

 ends. On the posterior wall of each slit there is a prominent transverse ridge, 

 containing a groove which leads into the canal of the cerebral organ. 



The upper extremity of the dorsal ganglion of the brain on either side ends 

 immediately iu front of the cerebral organ. In the anterior and upper part of the 

 dorsal ganglia, the largest or " giant " type (Burger) of ganglion-cells are extra- 

 ordinarily well seen, and are of very large size in proportion to the whole brain. 



The cerebral organs (PL II, fig. 4, C.O.) are well-developed, large, and abundantly 

 supplied with glands. On their inner and dorsal sides they are closely surrounded by 

 the lateral portions of the cephalic, blood-sinus. 



The lateral nerves, with their investment of ganglionic cells, run out almost at 

 right angles to the long axis of the animal for a considerable distance on leaving the 

 brain (PL II, fig. 4, L.N.), and then turn back to run in the usual manner along the 

 sides. They are very stout, and lie somewhat towards the ventral side of the animal 

 (PL II, fig." 2, L.N.). 



There is a complete plexus of nervous tissue (PL II, fig. 2, N.P.) immediately 

 outside the circular muscles of the body-wall, and a small dorsal nerve in this layer, in 

 the middle line, as in L. forniyatit*. 



Genital OiyaiiK. In a female specimen examined, the gonads appear to form a 

 continuous series along either side of the worm (PL II, fig. 5, G.). They compress 

 the gut between them, and are not separated from their neighbours by any 

 lateral gut-caeca. The eggs contained in this individual measure about 0'2 mm. in 

 diameter. 



I am unable, to give any account of the arrangement of the genital organs in 

 the male. 



Note : It may be remarked that there is nothing in my description of this form contradictory to the 

 siippnsitiim that it is identical with Cerebratiilim valitlus, Burger, from South Georgia. On the other hand, 

 the description (1893) of the latter species is based upon one specimen only, and is so brief that it would 

 ! scarcely possible to determine the species from it, and moreover no figures are given. Hence I ha\c 

 not hesitated to regard the " Terra Nova '' material in the light of a new species. 



