ON AMPHIPORUS SPECTABILIS. 285 
dinal vertical section be made through the proboscidian sheath 
of this form as seen in Drepanophorus rubrostriatus, Hu- 
brecht (Plate XIV, fig. 5), it is found that the wall is per- 
forated near the dorsal curve by a definite series of apertures 
(e a) on each side—a fact hitherto unknown in Nemertean 
anatomy. ‘The peculiar arrangement of the longitudinal and 
circular fibres, which intermix, except at the circumference, 
is therefore probably in relation with this condition. Atten- 
tion was first directed to the subject by observing a canal 
passing out in transverse section, and it is probable that a 
similar view has caused Dr. Hubrecht to represent a lateral 
separation by curved fibres on each side of a transverse 
section in his Plate II, fig. 4.1 The proboscidian chamber 
(cavity of the sheath), with its rich supply of fluids and cor- 
puscles, thus in all probability elaborates the blood, which then 
enters the trunks constituting the vascular system proper. The 
anatomy and physiology of the proboscidian sheath, its cavity 
and contents, and the study of the circulatory system in the 
living animal, afford an interesting field for further minute 
investigation. The size of the definitely formed proboscidian 
corpuscles merits special attention with regard to their pas- 
sage outwards through the lateral trunks. In the ordinary 
Ewnop.a they are very large, whereas in this species they are 
probably smaller, unless it happens that the larger bodies 
remain in the sheath-cavity. ‘The proboscidian sheaths were 
examined specially in A. pulcher and A. hastatus, but no trace 
of such apertures was visible. ‘The coarse nature of the 
encircling and other fibres of these sheaths sometimes 
prevents certainty of examination, but though a minute aper- 
ture therein might have been overlooked, it could not have 
escaped notice in a section of the superficial fibres, or the 
translucent region immediately external (where the vessels 
are very conspicuous in Drepanophorus). In the living 
Enopia formerly investigated, all trace of such arrangement 
was absent. In ordinary transverse sections of Dr. Hubrecht’s 
specimen there are within the longitudinal muscular coat on 
each side of the proboscidian sheath one or two large well- 
definedareas, which may be connected with this system. There 
are also numerous transverse vascular branches in Amphiporus 
pulcher ; and in A. hastatus a second longitudinal trunk 
(Plate XV, fig. 2, v’) occurs above the lateral nerve. 
Dr. Hubrecht observes with regard to the circulation in 
Lineide that he cannot agree with me “ in regarding the posi- 
tion of these blood-vessels as quite constant.” I am not 
‘ © Aanteekeningen,’ &c, 
