280 W. C. M’INTOSH. 
linearis, and Carinella Armandi, but, so far as at present 
known, this is the only species in which such fine transverse 
divisions of the fasciculi have been described. It is not 
unlikely that the arrangement may occur in other southern 
Enopia. ‘The muscular bundles are usually composed of 
rather coarse fibrils on transverse section, whereas in this 
form they are small and arranged in a pennate manner. The 
nearest, perhaps, is Amphiporus hastatus, in which both the 
circular and longitudinal muscular fibres are arranged in very 
narrow and regular rows (Pl. XIV, fig. 2), and this species 
further shows very complete development of the two thin 
decussating layers, ¢ e and ¢ 0, outside the longitudinal coat. 
In many longitudinal vertical sections the impression con- 
veyed with regard to the inner was that its fibres were more 
transversely placed than in the exterior stratum. A. hastatus 
is a large and powerful species, and the conditions of its 
existence (for it occasionally burrows in sand) may have 
some connection with this arrangement. 
In Lineus gesserensis there is anteriorly a thin layer of 
circular muscular fibres immediately beneath the basement- 
layer, the pressure of which had formerly been overlooked. 
3. Proboscidian Sheath. 
The sheath for the proboscis slightly differs in muscular 
structure from the typical ENopra, being composed ex- 
ternally of circular fibres (Pl. XIV, fig. 1, o a) and internally 
of longitudinal, o 6, many fibres of the latter, however, 
mixing with the circular coat, but not reaching its exterior 
region. Both kinds are largely developed and in marked 
contrast with the finely arranged and somewhat pennate 
* fasciculi of the circular and longitudinal muscles of the 
body-wall. The figures of my friend Dr. Hubrecht (op. 
cit., Pl. IL., figs. 4 and 5) appear, however, to be somewhat 
diagrammatic, while the remark’ that the proboscidian sheath 
in A. spectabilis (or Drepanophorus) is “ chiefly composed of 
circular fibres intermixed with longitudinal bundles” re- 
quires the foregoing description, and the observation that 
this form does not present the well-defined demarcation 
between the layers usually characteristic of the ENopna. 
Coating the internal surface of the chamber is a structure 
which is faintly developed in the ordinary Enopra 
(even in Amphiporus pulcher), viz., a mucous layer which 
presents in transverse sections (fig. 1, oc) a frilled 
or somewhat papillose aspect, the free margins being 
See present Number of the ‘Quart. Journ, Mier. Sc.,’ p. 125. 
