ON AMPHIPORUS SPECTABILIS. 279 
verse section) which runs throughout the length of the 
body. I have not seen this arrangement in other Nemerteans, 
and its function is unknown. Dr. Hubrecht and M. Marion 
have not yet noticed it. No mention was made of “ flask- 
shaped glands ” in my descriptions of the cutaneous system 
of the ANopLA, because such a termdid not appear to apply 
to any structure observed. 
Muscles of the Body-wall. 
The circular or external muscular layer in A. spectabilis 
(c, fig 1) presents in longitudinal section a series of definite 
rows, and the fasciculi have a somewhat pennate arrange- 
ment. M. Marion says they differ completely from the 
longitudinal fibres (in the absence of the pennate arrange- 
ment), but he can only refer to the respective appearances 
observed in transverse sections of the body-wall. Within 
the circular are two thin strata, ¢ e and ¢ 0, which represent 
in a somewhat less pronounced degree the decussating layers 
so well seen in Amphiporus hastatus. Such appear ‘to have 
escaped the notice of Dr. Hubrecht and M. Marien. The 
great longitudinal layer, d (fig. 1) has its fasciculi, in trans- 
verse sections, also arranged in definite though much longer 
rows than the circular (in longitudinal sections), groups of 
rows, moreover, being, as usual, marked off by somewhat 
regularly disposed radiating bands, which pass from the 
outer layers inwards to the alimentary region. Dr. Hubrecht 
thinks I have undervalued the “ inter-fascicular substance ” 
which he says ‘is a kind of fibrous connective tissue.” 
It has been often alluded to and figured in my observations, 
and since an opportunity is now afforded I shall do more 
justice to the fibres which pass from wall to wall (emerging 
between the rows of fasciculi) by stating that they are 
muscular in many of the Enorra and also in many of the 
AnopLa. In longitudinal vertical sections of the large Lineide 
these interlacing muscles map out, for instance, “the great 
longitudinal layer into a kind of meshwork. _ Their connec- 
tion with the hyaline and fibrous tissue of the body-cavity 
will be noticed elsewhere, especially in relation with the 
generative organs in A. spectabilis. M. Marion first pointed 
out the somewhat pennate arrangement of the longitudinal 
muscular layer (Gn transverse section) and its resemblance 
to the condition in the Oligocheta. The fasciculi in the 
Nemertean are more slender and linear as well as less 
regular. ‘Lhe linear grouping of these fibres is common in 
the Nemerteans, such as in Valencinia lineformis, Carinella 
