ON THE ANGUILLULID^. 161 



quire to be transferred to a distinct though nearly allied genus. Its present position 

 may be looked upon merely as provisional. 



27. ODONTOBIUS, Roussel. 

 Gen. Char. " Body thread-like ; anterior extremity more or less narrowed ; posterior 

 obtusely or sharply pointed, ending in a small papilla. Around the mouth and on 



■ anterior part of body are several cirri. On the hinder part of the body of the 

 male, around the genital opening, are one or two rows of roundish integumental 

 prominences. 



" Skin colourless or of a yellowish-green colour, occasionally iridescent. External in- 

 tegument smooth or transversely striped. CEsophagus cylindrical, widening slightly pos- 

 teriorly ; external layer or sheath composed of a finely granular mass, or cylindrical cells. 



" Vagina variable in position. Lateral lines present. Gland (ventral ?) of anterior part 

 of body doubtful. Tail-glands consisting of an agglomeration of cells. 



" Two spicules, with an anterior accessory organ', or two pairs of spicules, one large 

 and one small." — Eberth, "[Inters, iiber Nemat. p. 27. 



This description is the one given by Eberth, which I have inserted rather than, that 

 of Roussel, from its containing more details, though even these are insufficient accurately 

 to characterize and fix the position of the genus. Eberth naturally enough objects to 

 Diesing's having in his recent " Revision der Nematoden" placed this genus amongst 

 his subfamily AiiguillnlidcB, since Roussel's Odontobius was distinctly stated to be pro- 

 vided with cirri around the mouth. Eberth is, however, himself uncertain what 

 systematic place to assign to this genus, but says that he includes in it several free 

 Nematoids which, from the appearance of small teeth ^ in the mouth, are distinguished 

 from those of Amhlyara, Phanoglene, Michelidium, and Oncholaimus, and, through the 

 want of ocelli, from those of JEnoplus. 



Whether the original animal described by Roussel de Vauzeme, and found by him in 

 or- on the mucous membrane about the base of the whalebone in Balcena Anstralis, is* 

 rightly included amongst the free Nematodes is a point about which I am still doubtful ; 

 but, as it seems quite possible that one of these animals might be met with in such a 

 situation, I have retained it amongst them, and have refrained from altering the designa- 

 tion of three of the species placed by Eberth in this genus, though one of them seems to 

 differ in some important respects from the other two. 



1. O. CETij Roussel. 



Odontobius Ceti, Roussel de Vauzeme, in Annal. des Sc. Nat. 2 ser. i. .326, tab. ix. 1-5 A ; et Froriep's 

 Notiz. xxxvii. 1, figs. .3-6 ; Isis, 1836, p. 512.— Siebold, in Wiegmann's Archiv, 1835, i. 336.— Nord- 

 mann, in Lamarck's Anim. sans Vert. 2'"= edit. iii. 669. — Dujardin, Hist. Nat. des Helminthes, 292. 



" Corpus capillare, extremitate caudali involuta. Caput corpore continuum. Os termi- 



nale, orbiculare, dentibus cornels 3-6. Penis . . . . ; apertura genitalis feminea 



Longit. ad 2\"'. 



1 This seems only to have been met with in Odontobius acuminatus, which I have transferred to the genus Anti- 

 coma, so that the latter part of this sentence only must now be considered as apphcable to the geuas Odontobius. 



^ He omits to mention these in his generic description given above. 

 VOL. XXV. - Y 



