90 E. RAY LANKESTER, ON GREGARINIDS. 
The smallest of them is merely a cell containing granules 
and a nucleus. In the second a septum is seen dividing the 
cell into two halves. The third form has all the appearance 
of a true Gregarina in a very young stage. Leidy has seen 
such bodies in the intestine of Julus. 
M. Ed. Claparéde, in his ‘ Recherches Anatomiques 
sur les Annelides, Turbellaries,’ &c., describes several new 
forms of Gregarina from three species of Annelida. The 
most interesting of these is from the intestine of Capitella 
capitata. It is unilocular, contains granules and a vesicle, 
and has the form of an anchor; its length is °35 mm. 
This species appears to have been seen by Leuckart, who 
named it G. sagittata.* In the intestine of a Phyllodoce, 
M. Claparéde frequently met with a species of Gregarina, 
striated longitudinally, somewhat fusiform in shape, and very 
active; its length was ‘41mm. Some of these organisms 
contained Pseudo-navicule; other smaller forms were abun- 
dant, which were not striated—probably the young of the 
preceding. In the intestine of Pachydrillus semifuscus 
another species was found; very minute, containmg gra- 
nules and a vesicle: its average length was ‘(O5mm. M. 
Claparéde does not name these last two species, but in the 
catalogue below I have given them specific names, in order to 
complete the list. 
In the intestine of Serpula contortuplicata I have met with 
a species of Gregarina in some numbers (figs. 4—7). In its 
general form it approaches the species described by M. Cla- 
paréde from the intestine of Phyllodoce ; it is striated longi- 
tudinally, contains a vesicle and very minute granules. The 
average length is =1,th inch ; its movements are slow but con- 
stant ; in some specimens there was an anterior prolongation 
of the sac-membrane, which, however, was not persistent. I 
have given the specific name “ Serpule’’ to this species, as I 
believe it has not before been described. 
In the intestine of Aphrodite aculeata I have found an 
elongated, fusiform Gregarina, of large size (figs. 1—8), con- 
taining numerous granules and a clear vesicle. It measured 
='; inch in length, and was provided with an elongated ap- 
pendage one third the length of the body, the extremity of 
which was involuted and terminated by a circular protube- 
rance. This is the only unilocular form of Gregarina which 
at present has been found provided with a proboscis; it is 
interesting, too, inasmuch as the existence of two membranes 
composing the sac is evident. The external one envelopes 
the whole animal, and forms the involutions at the extremity 
* Wiegman’s ‘ Archiv,’ 1861, Bericht, &c., for 1859. 
