110 ANATOMY OF THE ANOPLA. 



right, and so indicated this separation on that side. The presence of the trumpet-shaped mouths 

 of the ducts of the cephalic sacs in such a preparation shows that these bodies are posterior and 

 not yet reached by the instrument. Longitudinal sections of the head of the worm exhibit 

 the positions of the ganglia and the cephalic sacs with great clearness, each of the former 

 often presenting different appearances on the respective sides from obliquity of section, but the 

 posterior borders are always distinctly separated from the sacs (Plate XVIII, fig. 10). 



In all sections of the ganglia a peculiar change occurs after mounting in chloride of 

 calcium, the oily matter of the tissue collecting in curious streaks and circles, and apparently at 

 some parts resisting the penetration of the fluid. 



Considerable difficulty is experienced in making out the anterior branches of the ganglia, 

 from the opacity of the snout ; but three or four trunks of note are occasionally apparent — two 

 large branches superiorly, and one or two smaller beneath. Some twigs seemed to proceed in the 

 direction of the eye-specks, but their ultimate distribution could not be traced. 



Each great nerve-trunk (Plate XIX, fig. 1, n) leaves the posterior end of the inferior lobe as 

 in the Enopla, proceeds along the side of the body, and terminates at the tip of the tail. The 

 calibre of the cords slightly diminishes as they course backwards ; and their position is nearer the 

 ventral than the dorsal surface. Branches probably exist, but only faint traces of such are seen 

 in the longitudinal sections, for the opacity of the textures in the living animal prevents their being 

 satisfactorily made out. The trunks are imbedded in a fibro-granular matrix (Plate XXI, fig. 6, 

 ri) of the same reddish hue, and have, in addition, the proper sheath {neurilemma) of the nerve. 

 In some pale species they are marked externally as two pinkish dorsal streaks. These trunks, as 

 already indicated, have a very different position from the nerves in the Enopla, being situated 

 outside the circular muscular layer, and between it and the great longitudinal. Two muscular 

 coats (circular and internal longitudinal) thus intervene between the nerves and the body-cavity 

 and its contents, whereas in the Enopla the nerves are within all the muscular layers. 



The general arrangement of the cephalic ganglia in Carinella annwlata agrees with that in 

 Lineus, so that a special description is unnecessary. The lateral nerve-trunks lie between the 

 basement-layer and the external (circular) muscular coat of the body-wall (Plate XXII, fig. 2, n). 

 In Falencinia lineformis a variation is observed, since the nerves do not quite reach the external 

 border of the great longitudinal muscular layer. 



The chief peculiarity of the ganglia in Cepliahtlrix (Plate XIX, fig. 9), as first pointed out 

 by Prof. Keferstein, is the advance of the almond-shaped upper lobes, so that the superior 

 commissure is quite in front of the inferior. The lateral nerves are placed between an 

 isolated longitudinal fasciculus and the great longitudinal muscular coat of the worm (Plate 

 XXI, fig. 2). 



Mr. H. Goodsir criticises the description given by M. de Quatrefages of the nervous system 

 in Serpentaria and Nemertes, and, like (Ersted, denies its existence altogether, averring that 

 microscopically the so-called nerve-trunks show no nervous elements at all, but are the testicles of 

 the worms. I fear, however, this worthy naturalist depended rather upon analogy than actual 

 observation in this case. He accounts for the nervous fibres seen by Rathke (the first who 

 correctly described the ganglia in Lineus) passing from the cephalic ganglia to the narrow 

 slits on each side of the head, by supposing them to be seminal tubes on their way to the furrows 

 (his seminal apertures). M. de Quatrefages confines his examinations chiefly to the ganglia of 

 the Enopla. Frey and Leuckart, again, confound the cephalic sacs with the posterior part of the 



