250 A. A. W. HUBRECHT. 
(Delle Ch.), Lineus longissimus (Sowerby), Lineus bilineatus 
(Delle Ch.), and Borlasia olivacea (‘Lhompson). 
From the enoplan sub-division I had at my disposal 
several species of the genus Ommatoplea (Dies.), as well as 
three new species which I have put together in the genus 
Drepanophorus (n. g.) and which are distinguished by the 
structure of their stylet and stylet region differing entirely 
from the typical form found in all other Enopla, This 
curious deviation will be discussed in the proper place. 
Dermal Tissues and Muscular Layers of the Body. 
The difference existing with respect to these tissues be- 
tween the enoplan and the anoplan forms (Mr. MacIntosh’s 
Ommatopleans and Borlasians) is great indeed, showing 
that subdivision of the order (as first proposed by Max 
Schultze) to be a very natural one. Yet the principal inves- 
tigators of the subject, such as Keferstein and Quatrefages, 
confounded the structures in the one with those in the other 
and it remained for Mr. MacIntosh to point out with great 
clearness the obvious differences. He reduces the number 
of muscular layers in the Enopla to an external cir- 
cular one and an internal longitudinal one of greater 
thickness, and shows that the Anopla are, on the con- 
trary, provided with an external as well as an internal 
longitudinal, with an interjacent circular layer. Keferstein’s 
external circular layer is shown to be a structureless basement 
layer of the cutis. My observations tend fully to confirm 
these views. Many preparations of unarmed Meckelias had 
the external epidermic layer thickly provided with flask- 
shaped glands opening externally, which are mentioned by 
Keferstein, but about which Mr. MacIntosh is silent. 
The interfascicular substance which plays so large a part 
in the structure of the body wall is rather undervalued by 
Mr. MacIntosh. It is a kind of fibrous connective tissue, 
surrounds the dermal structures, carries the pigment and 
forms layers between the cuticular and muscular layers cor- 
responding to that separate basement layer, confounded by 
Keferstein with a muscular one. From this stratum numerous 
separate fibres can be traced entering into the interspaces 
between the fascicules of outer longitudinal muscles, con- 
tinuing their way downwards through the circular and in- 
ternal longitudinal layer, finally enterimg into the body- 
cavity, traversing this, and again completely piercing the 
opposite muscular body-wall, to find their way back into the 
dermal tissue. 
Still the separate fibres of this fibro-elastic stroma do not 
