250 Prof. H. James-Clark on the Spongie ciliate 
in the Exe and in the canal near Exeter, throughout the summer 
months; but, by attaching itself to plants which die down in 
the autumn, the specimens are all swept away by the winter 
floods. 
XX XIITI.— On the Spongie ciliate as Infusoria flagellata; or 
Observations on the Structure, Animality, and Relationship 
of Leucosolenia botryoides, Bowerbank. By H. JAMEs- 
CuiarK, A.B., B.S., Professor of Natural History in the 
Agricultural College of Pennsylvania. 
{Continued from p. 215.] 
§ 12. Astasia trichophora, Clap. Pl. VI. figs. 45, 46. 
The transition from the mononematous Monas, Codosiga, 
Leucosolenia, &c. to those heteronematous Flagellata which 
possess at the same time a proboscidiform and a gubernacli- 
form flagellum is most aptly exemplified by that curious mi- 
metic combination of Ameba and Anisonema known as As- 
tasia trichophora, Clap. (Trachelius trichophorus, Ehr.). At 
first sight it appears to be capable of all the abrupt retrogres- 
sive motions and short turnings of an Andsonema (figs. 65-69), 
without being endowed with a similar means of locomotion. 
One is not long, however, in discovering the homologue of the 
trail (fl?) or rudder (gubernaclum) of the latter in the posterior 
abdominal, triangular prolongation (fig. 45, fl?) of the body of 
the former. That this is the true interpretation of the pro- 
longation is warranted not only by the use to which it is put, 
as a sort of point d’apput during the amceboid retroversions of 
the body, but also by its persistent form whilst the animal is 
contorted into a shapeless writhing mass. In the midst of the 
paucity of distinctive topography, we are also furnished b 
this organ, if I may so call it, with a basis of ready discrimi- 
nation between the practically ventral and dorsal sides of the 
body; for, although it may not lie strictly in the central line 
of progress during reptation (nor could we expect to find it 
there upon being referred to its homological relation to the 
asymmetrically attached gubernaclum of Anisonema), it none 
the less belongs to the reptant side of the animal, and, as it 
were, controls its motions and acts as a keel, upon which the 
osterior end of the body vibrates and reels from side to side. 
Finally, in reference to this point, it may be added that this 
species does not swim, properly speaking, nor has it the cha- 
racter of the revolving natant forms, such as Dujardin sepa- 
rated from the Astasia of Ehrenberg and described under the 
name of Peranema. 
