986 Ww. C. M’ENTOSH. 
aware that any such limitation was made, and the figures 
show very great variety in this respect. In anew Valencinia,} 
recently described, the changes which take place in the posi- 
tion of the trunks in their course from the snout backwards 
to the tail are very considerable, and perhaps other Carinellide 
may show this arrangement in a more pronounced form. It is 
of little importance in the Lineide to place much weight on 
the absolute position of the ventral trunks, but they certainly 
all fall under one plan. 
6. Nervous System. 
Dr. Hubrecht observes that the lateral nerve-trunks in 
Amphiporus spectabilis (his Drepanophorus) have considerably 
approached the median ventral axis of the animal. ‘Though 
this is the case, the degree of change does not alter in any 
respect the relationship to the typical Amphiporide. He 
has misunderstood the remarks about the position of the 
nerve-trunks in the Meckelian type (Trans. R. Soc. Edin.), 
because, following in my earlier paper Dr. Johnston’s 
Catalogue, Carinella annulata is there indicated by the term 
Meckelia annulata. He does not appear to be acquainted 
with the Carinellide, whose nerve-trunks occupy the position 
described. 
Dr. Hubrecht’s remarks centre round two chief points in 
regard to the nervous system. He states, in the first place, 
that the cephalic sacs of the Lineide are continuous with 
the ganglia, and in the present paper he has revived the 
views of A. 8. CGirsted and others, with a little modification, 
that they act “‘as a special respiratory apparatus providing 
the cephalic hemoglobin with fresh supplies of oxygen.” 
It is curious, however, that his figure (Pl. II, fig. 8) of the 
organs in Meckelia somatotomus (one of the Linetdaz) shows 
not a trace of the ciliated ducts, which occur in all the 
British and foreign representatives of the family examined.? 
The intimate relation of these sacs with the ganglia is well 
known, but after again glancing at my preparations, and 
consulting the observations and drawings of the living 
Lineus gesserensis (in which the organs are most distinctly 
1 Vide ‘ Proceed. Linnean Soc.’ 1875. 
* Moreover, an explanation of this figure is required, since the great 
commissure is superior and the small inferior, while the reverse is the case 
in nature. Ina more recent publication, with a supplementary plate, the 
ducts are added to the organs, but they are represented as entering the sacs 
superiorly in the middle line, whereas they usually enter at the inferior and 
outer border. The same dubious arrangement of the ganglionic commissures 
persists in this figure (‘ Niederlandisches Archiv f. Zool.,’ Bd. II, Heft 3, 
Tat.xi, f. 3); 
