244 Ml". II. J. Carter un Ploesconia and Kerona. 



commencement of the gill, where they appear to form lateral 

 extensions of its anterior bars. Abdominal cavity containing 

 sarcode charged with molecules, refractive hepatic (?) oil (?)- 

 globules, and, when also present, digestive spaces enclosing frag- 

 ments of food. No hepatic cells. Anal orifice and contract- 

 ing vesicle marginal, situated together on the right side, at the 

 junction of the posterior with the middle third of the body. 

 Nucleus long, cylindrical, situated circumferentially, and ex- 

 tending three-fourths round the body, that is, commencing 

 posteriorly, passing round by the left side, and ending just in 

 front of the contracting vesicle. Length about l-134th of an 

 inch, but variable. 

 Hab. Both fresh and salt water, feeding on small animalcules, 



Diatomacese and Algffi. 

 Loc. Island of Bombay and Europe. 



Obs. Although in the illustrations (Pl.VI. figs. 1 & 3) the dorsal 

 is much raised above the ventral surface, yet it should be remem- 

 bered that this is caused by the abdominal cavity being dis- 

 tended with embryonic cells, and that when these are absent the 

 animalcule is frequently so fiat that the two surfaces are nearly 

 in contact. 



I am not quite certain about the number of the anterior set 

 of legs, whether it be eight or nine, but I think the former. 

 Sometimes also five or six longitudinal lines are visible, appa- 

 rently on the ventral surface, where they seem to divide the 

 posterior legs from each other at their bases ; but they do not 

 appear to constitute a specific difference, or to be peculiar to 

 P. truncata, for they are more or less present in the other 

 Plcesconice which have come under my observation, although 

 only now and then perceptible (fig. 4 w). The basal articulations 

 are only seen under favourable circumstances, and even then 

 but very imperfectly, as well as the hairs into which the pos- 

 terior legs are cleft ; so that the microscopist must not expect to 

 see these features immediately, nor be surprised if he find one or 

 more of the anterior legs cleft, in opposition to what I have 

 stated ; for it was only after long watching that I met with indi- 

 viduals of P. truncata in which this feature was disclosed in the 

 posterior ones. Dr. Lachmann has noticed the articulations at 

 the base of the short legs or ''styli " in the Ewplota, and that one 

 of them in E. patella has been observed to bear " setiform 

 branches ;" also that the posterior legs or " uncini " are " cleft at 

 the end in some species, as for example in Euplutes patella^." 



The ladder-like structure (fig. S b), to which I have applied 

 the name of " giW," from its branchial appearance, seems to pre- 



* Annals, vol. xix. p. 217, 1857. 



