182 Miscellaneous. 
standing this low organization, the body is metamerized, and the 
metameres even present remarkable differentiations. The first ring 
terminates anteriorly in a blunt cone and bears a tuft of rigid 
sete. It is followed by a cylindrical ring of the same length, the 
whole surface of which is roughened with papille, apparently dis- 
posed in ten longitudinal rows; this is the only part of the body 
which does not present vibratile cilia. The third ring is larger than 
the first two taken together ; it widens gently towards its posterior 
extremity. The fourth metamere is of the same dimensions as the 
papilliferous ring ; it is followed by a terminal ring, furnished with 
longer cilia at its posterior extremity, conical and subdivided into 
two metameres less distinct than the preceding ones. Such is the 
elongated form. The last rings form a sort of club with which the 
animal beats the water, independently of the movements of the 
cilia, and by sudden blows which one might think due to the action 
of muscular elements. The ovoid form differs from the elongated 
form only in its less length and greater breadth; but I have ascer- 
tained -that it is not the result of a contraction of the animal. 
Perhaps it is a sexual form, perhaps also a young state of the 
parasite. I give this strange animal the name of Rhapalura ophio- 
come. 
A parasite of the same group is also met with at Wimereux, in a 
Nemertean, Lineus gesserensis, O, F. Miller, which is very common, 
as well as its variety L. sanguineus, under the stones of the muddy 
places in the neighbourhood of the Tour de Croi. This animal 
differs, however, sufficiently from Rhopalura to constitute a dis- 
tinct genus ; the papilliferous ring is replaced by two very narrow 
ciliated rings; the median portion of the body generally has six 
nearly equal metameres ; the terminal club is formed of three rings ; 
the anterior part, moreover, bears a tuft of rigid cilia. There are 
also an elongated and an ovoid form. M‘Intosh has said a few 
words on this parasite in his fine monograph of the British Nemer- 
teans* ; I therefore propose to give it the name of Jntoshia liner. 
Lastly a species evidently belonging to the same genus has been 
figured without description by Keferstein+, who met with it at 
St. Malo as a parasite in the digestive tube of a Planarian (Lepto- 
plana tremellaris) which is’ also very common at Wimereux. I 
give this species, which is very nearly allied to the preceding, the 
name of Jntoshia leptoplane. 
In the absence of sufficient embryogenical evidence, it is impossible 
for me at present to assign these animals to the definitive place which 
they must occupy in the classification. By the name OrrHonzctipa 
I have desired to recall their progression, which is so characteristic 
that it would of itself suffice for their recognition among the para- 
sites with which they might be confounded. Provisionally I think 
that the Orthonectida should be ranged above the Dicyemida and 
near the Gastrotricha; the latter and the degraded Rotifers also 
* M‘Intosh, ‘A Monograph of the British Annelids: the Nemerteans,’ 
1874, p. 129, pl. xviii. figs. 17-19. 
+ Keferstein, ‘Beitrage zur Anatomie und Entwickelungsgeschichte 
einiger Seeplanarien von St.-Malo,’ Taf. ii. fig. 8. 
