108 H. CHARLTON BASTIAN ON THE STRUCTURE AND 
not been able to discover any trace of it, this may be due to the fact that the worms 
examined were not recent specimens, but had been preserved in spirits of wine. 
The integuments of the Nematoid worms have been described by Von Siebold, Dujardin, 
Owen, and other writers, as composed of a structureless epidermis, and a corium made up 
‘of layers of longitudinal and oblique decussating fibres; but, after a most careful exami- 
nation, I have been unable to discover that any such distinction can be drawn between 
the different portions of the integument of the Guineaworm—the whole thickness being 
almost identical in structure, and apparently composed of successive excreted * epidermic 
layers. I think it will be possible to show also that what appear to be layers of decussating 
fibres, in the Guineaworm and some other Nematoids that I have examined, are not 
such in reality. A true corium or enderon, as before stated, I have failed to recognise. 
The average thickness of the integuments is 435th of an inch, though it is considerably 
thinner towards either extremity of the body. It may be divided into two principal 
parts—an external portion with transverse markings, constituting about one-half of the 
whole thickness, not divisible into lamelle ; and an internal portion, made up of about 
thirty very delicate lamelle, having longitudinal or oblique markings. 
The ezternal portion of the integument is composed of a thick, chitinous layer, tough, 
elastie, transparent, and perfectly structureless, save that it presents transverse markings 
at intervals. These lines (Pl. XXI. fig. 8) have an average distance of j4ls5th of an 
inch from one another, though near either extremity of the worm they are as little as 
sooth of an inch apart, the distance between the lines gradually diminishing up to this 
point. They are about zj55th of an inch in breadth, and easily recognisable when most 
of the lamelle covering them internally have been stripped off. They vary slightly in 
their distance from one another, are wavy, but do not preserve any parallelism between 
themselves; and moreover they frequently join one another or bifurcate, so that they 
by no means form perfect circles round the body. 
: The external surface of the integument seems perfectly smooth, there being no appre- 
ciable depressions corresponding to the annulose markings such as may be seen to a 
slight extent in Ascaris lumbricoides and A. mystax; but there is some considerable 
alteration in the refractive power of the membrane in these situations, as when seen 
a little beyond the proper focal distance these markings become most distinct, appearing 
as bright white lines. : 
The internal portion is composed of three different sets of very delicate lamellæ, each 
being transparent, glass-like, and structureless with the exception of certain faint recti- 
linear markings at regular intervals, which correspond in breadth to those between the 
bg مم‎ of the outer portion of the integument, viz. about Tooth of an inch. 
, o seem due to some variation in structure producing an alteration in the 
refractive power of the lamelle. 
ed "a d * à composed of about ten superimposed lamellz, the markings 
oppida eo XI ongitudinal, whilst those of the inner two sets are oblique, 2 
م‎ E : « en seen superimposed, the markings of the middle set of lamellze 
intersect those of the internal set at an angle of about 85°, or nearly at a 
* Huxley, Art. « Tegumentary Organs,” Cyclop. of Nat. & Phys. pt. xlvii. 1855, p. 484. 
