new Forms of American Rotifera. 19 



entire length ; a small gastric gland is present on each rontal 

 shoulder of the stomach ; contractile vesicle in the median 

 line, ventrad to the intestine, oval in contour and conspicuous 

 near the posterior body-margin ; lateral canals present, with 

 but four flame-cells visible on each side ; two small elongate- 

 ovate foot-glands present ; animal's movements constantly 

 writhing and vermicular when unaided by the auricles, but 

 with these appendages rapid, headlong, and seemingly without 

 choice of direction. 



Length about y^ inch. 



Intestinal canal usually gorged with yellowish-brown food 

 materials. 



The species is readily recognizable not only by its form 

 and by the lateral crenulations, but especially by the peculiar 

 granular region of the brain, that particular part being in 

 form not unjustly comparable to a pendulum with a sub- 

 spherical bob, or to a cord with a round weight attached at 

 one end. These granules, which I have not seen in any other 

 portion of the ganglion, are freely movable on one another 

 and in form vary from elongate-ovate to subfusiform. They 

 are probably concretions of lime as so commonly observed in 

 the cerebral ganglia of other Notomatid^. They ai-e here 

 contained in a tubular case or sheath, and may be motionless 

 by reason of their number. Even when these granules are 

 absent the region which they will at some time occupy is 

 always plainly visible. They seem to be the result of a 

 crystallization within a liquid enclosed by a special membrane 

 within the nerve-mass. The clavate form of the mass 

 suggested the specific name. 



Metopidia coUaris, sp. n. (PI. VII. figs. 3 and 4.) 



Lorica suboval, depressed, the dorsum rounded, the central 

 region a slightly flattened more or less obovate space, whose 

 margins converge posteriorly into a central ridge extend- 

 ing to the posterior border of the lorica, the lateral regions 

 of the lorica falling away rather rapidly to the convex edge, 

 thus giving the entire dorsum a somewhat tectiform aspect, 

 frequently increased by the presence of a central longitudinal 

 ridge ; ventrum flattened ; dorsal frontal margin concave, 

 the ventral deeply excavate ; the frontal angle on each side 

 prolonged as a conspicuous acuminate process; a narrow, 

 coarsely stippled, collar-like band encircling the entire ante- 

 rior margin of the lorica ; posterior dorsal border narrow, 

 slightly and evenly concave, the ventral margin conspicuously 

 excavate into a deep narrow sulcus, its lateral borders but 



2* 



