80 MACALISTER, ON ASCARIS DACTYLURIS. 
of its obscurely bi- or trilobate mouth and its unequal spicula ; 
he does not enter into any further details respecting its struc- 
ture, but expresses his regret at not having been able to fulfil 
his original intention of thoroughly examining its internal 
organization. <A few notices of this species likewise occur in 
Siebold’s ‘ Anatomy of Invertebrates,’ but, with these excep- 
tions, I am not aware of there being any special anatomical 
description of this creature extant. 
The specimens which I have been enabled to examine are 
whitish in colour, mostly straight, though at times a little 
curved at the distal extremity, and measuring as an average 
about two lines and three fifths in length, the range being 
from one line and a quarter, as a minimum, to five lines as 
a maximum ; the breadth in the centre varies from one tenth 
to one quarter of a line, and in some of the largest exceeded 
that amount. The males, which are very much fewer than 
the females (at least among those that I examined not one in 
fifty were males), are much smaller, and average in length a 
line and seven eighths ; they are more curved than the latter, 
and sometimes exhibit a partial dorsal constriction at the 
junction of the anterior and middle thirds. The females are 
usually about two and a half to three lines in length. 
The integument is transparent, wrinkled tranversely or 
annulated; but this appearance is not always distinct in 
recent specimens, or in those kept in aqueous solutions; 
when, however, they are immersed in any dense fluid, which 
will cause a rapid exosmosis, the animal becomes slightly 
shrivelled, and the annulations are then seen with the utmost 
clearness ; when placed in spirits of wine the integument be- 
comes firmer and less transparent, and the annulations also 
seen with considerable distinctness. A few longitudinal striz 
are visible on the outer layer, but they do not seem to be 
regular in their position or arrangement. Towards the taila 
considerable number of distinct oblique lines are occasionally 
seen radiating from the anus to the dorsal aspect, but they do 
not seem to be deeper than the superficial tegumentary layer ; 
they commence at the ventral line and extend symmetrically 
on either side of it towards the dorsal surface, but stop short 
about the middle of that aspect. Two lateral lines can be 
traced with great facility, commencing narrow at the head, 
widening slightly in the centre, and passing backwards to the 
posterior extremity or tail, where they also taper a little, and 
end near its tip by gradually diminishing ; but whether these 
lines be muscular, as Rudolphi thought, in other species of 
Ascaris, or vascular, as supposed by Eberth, or nervous, as 
imagined by Cuvier, Willis, and Cobbold, I could not even 
