ON THE ANGUILLULID^. 105 



Carter's generic name. Carter is inclined to believe that this JJrolabes 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 striae (most easily recognizable 

 in the young), but could not succeed in demonstrating such striae in Z7. palustris : to 

 him its integument appeared plain. 1 have since ascertained that the integument in 

 Dorylaimus stagualis and others of the same genus not only has no transverse strige, 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 TI. palustris, can be detected in the Dracunculus, 

 and also the fact that nothing answering to the peculiar lateral sacculi discovered 

 by myself 2 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 Gordiidce, 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. palustris, 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 oesophagus. 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. stagnaUs that I have become perfectly 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 striae, 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 striae, but also from the danger 

 of confounding the appearance of the longitudinal muscles as seen through the integument with actual markings of 

 this structure. 



- Transactions of the Linnean Society, vol. xxiv. pi. 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 Gordiidce. And if we 

 may rely upon existing information, the difference as regards important anatomical characters is infiuitely greater 

 between these animals and the Nematoids generally than between any two of the families composing this latter order. 



VOL. XXV. ■ P 



