ON THE ANGUILLULIDÆ. 105 
Carter's generic name. Carter is inclined to believe that this Urolabes palustris may be ` 
the antecedent condition of the Dracunculus, or Guinea-worm, which is so prevalent as a 
parasite in the island of Bombay. But my investigations have almost convinced me that 
this is impossible, and principally for a reason which also occurred to Mr. Carter, but of 
the precise importance of which he does not seem to have been aware. He knew that 
the integument of the Dracunculus presented transverse stris (most easily recognizable 
in the young), but could not succeed in demonstrating such stris in U. palustris: to 
him its integument appeared plain. I have since ascertained that the integument in 
Dorylaimus stagnalis and others of the same genus not only has no transverse stris, but 
is undoubtedly furnished with longitudinal ones'; and all my experience goes to prove 
that the nature of the integumental markings affords a constant character, not only of 
specific, but even of generic importance. Independently of this, there is the difficulty 
that no horny spear, such as exists in U. palustris, can be detected in the Dracunculus, 
and also the fact that nothing answering to the peculiar lateral sacculi discovered 
by myself? in the young Guinea-worms can be recognized in this, or has yet been found 
in any other species of Nematode, so far as I am aware, with the exception of Dicelis 
filaria, Dujardin. I may state, however, that from what I have seen of the anatomy of 
the Dracunculus and other members of the Nematoid order, I feel quite disposed to 
believe that its affinities are with these free Nematodes, and fully expect that one day 
this will be an established fact. I cannot but consider the step which Dr. Cobbold has 
taken in his recent work, of placing the Guinea-worm amongst the Gordiide, and 
constituting these a mere family of the order Nematoidea, as altogether a retrograde 
movement, and one almost in direct opposition to the existing state of our knowledge". 
We are much indebted to Carter for his descriptions of the male and female 
genital organs of U. palusíris, as well as for his account of the development of the 
spermatozoa. There appears to be no other representative of this genus Dorylaimus 
amongst the ten species described by him—five of which were marine, and five from 
fresh water. 
In all the Dorylaimi examined, which had not yet attained their full development, I 
observed a second and somewhat larger spear a short distance behind the one in situ, and 
contained within the walls of the esophagus. In due time this moves upwards in some 
obscure way, and finally displaces the other, just as the deciduous is replaced by the 
‘ It is from my observations on the anatomy of D. stagnalis that I have become perfeetly convinced that the integu- 
ment does present longitudinal, but no transverse markings. In this species I have frequently examined portions of 
integument freed from all other structures. But in the members of some other genera of free Nematoids not pre- 
senting transverse strie, I am in many cases doubtful whether the integument is perfectly plain or has longitudinal 
markings—and this not only on account of the greater difficulty of recognizing such striæ, but also from the danger 
of confounding the appearance of the longitudinal muscles as seen through the integument with actual markings of 
this structure. s 
* Transactions of the Linnean Society, vol. xxiv. pl. 22. figs. 57-60. 
* Nearly all the anatomical details of Dracunculus, so far as they are known, are in harmony with those of many 
typical Nematoids, whilst they differ considerably from those stated to obtain amongst the Gordiide. And if we 
may rely upon existing information, the difference as regards important anatomical characters is infinitely greater 
between these animals and the Nematoids generally than between any two of the families composing this latter order, 
VOL. Xxy. P 
