292 W. C, M’INTOSH. 
(cutis) is here bounded by a distinct basement-structure, for 
most of the circular muscular fibres have spread out to cross 
the region transversely some distance inwards. The basis- 
layer is extremely indistinct in contrast with that of the 
Nemerteans—both in transverse and longitudinal sections, 
and no allusion was made to it in the general remarks in 
connection with the Nemerteans. Mr. Moseley’s fine pre- 
parations, however, probably show it more satisfactorily. 
His observations having again drawn attention to the subject, 
it is found that in longitudinal sections (where it ought to 
come out boldly) careful examination indicates a termination 
of the hypodermic layer outside the circular muscular coat. 
‘That such a basis-layer, however, should fail to be the 
homologue of the basis or basement-layer in the Nemer- 
teans and Planarians is peculiar; the more so, as Mr. 
Moseley makes the circular muscular layer (immediately 
beneath) the homologue of the basis-layer in the Nemerteans 
and Planarians. ‘ Great stress,” he says, “‘ has been laid 
by various authors on the supposed fact, that whilst in Anne- 
lids, Nematoids, Trematodes, and, in fact, all higher worms, 
the external coat of the body was arranged circularly and the 
internal longitudinally, in 'Turbellarians the reverse was the 
ease; and the statement has been made in such a form that 
it really appeared as if an inversion of the muscular coats 
must be supposed in order to get at the proper homological 
relations of the muscular structures.” ‘‘ M‘Intosh lays great 
stress on the fact, that in Ommatoplea alba the circular 
muscles are external and the longitudinal internal, whilst in 
Borlasia the reverse is the case ; and accordingly he regards 
these two worms as belonging to very different types indeed.”? 
T certainly (and with greater emphasis) still regard the 
Amphiporide and Lineide as very different types of Ne- 
merteans; but, as before, this is based upon much more 
extensive data than the muscular system. The statements 
are not dependent on any theory, which, I fear, is the 
case with the view of the homology of the circular muscular 
fibres of Bipalium with the basis-layer of the Nemertean 
body-wall. Further, he observes —“ But the external 
circular coat of Ommatoplea is evidently the homologue 
of the thick external tunic of Borlasia, called by M‘Intosh 
the basement membrane, since in Ommatoplea there is 
said to be no basement membrane, and the external cir- 
cular muscular coat les immediately beneath the epidermis, 
as does the so-called basement membrane of Borlasia.” An 
error has evidently occurred here—probably due to the 
printer and the absence of Mr. Moseley, because it will be 
' Loe. cit., p. 310. 
