BEACHIONID^. 121 



(PI. XXX. fig. 9a). This is a little advance on the structure in Notcus quadricornis, in 

 which Kotiferon two distinct circular perforations, with smooth edges slightly raised 

 above the general level of the lorica, give passage to the antennal brushes. 



Length. Of lorica, ^J^j inch. Habitat. Near London; Birmingham; Dundee 

 (P.H.G.) ; Clifton (C.T.H.) ; pools of fresh water : not uncommon. 



Genu3 NOTEUS. 



GEN. CH. 'Loxica, facetted, and covered with raised points ; gibbous dorsalUj , flat 

 vcntrally ; foot obscurelij jointed ; toes moderately long ; ejes wantiiig. 



N. QUADBICORNIS. 



(PI. XXVIII. fig. 5.) 



Notcus quadricornis . . . Ehrenberg, Die Infus. 1838, p. 503, Taf. Ixii. fig. 1. 



... Leydig, Ucb. d. Bau d. Rcidcrth. 1854, p. 53, fig. 41. 



... Eckstein, Sieb. u. Eoll. Zcits. Bd. xxxix. 1883, p. 3'J4. 



„ „ ... Plate, Jcnaisc/i. ^ciYs./. AVijHr. Bd. xix. 1885, p. 05. 



The lorica of this handsome creature, the sole species of the genus, consists of two 

 saucer-like plates ; the dorsal one convex, facetted, and stippled ; the ventral concave 

 all round the edge but bulging in the middle, stippled and not tesselated. The front 

 of the ventral plate is a concave circular segment with a minutely serrated edge, and 

 the front of the dorsal plate has a similar, but unserrated, edge, with its outline broken 

 by two projecting strips of the lorica which curve gradually over the head. At the hind 

 end, the lorica is armed with two long, and nearly straight spines, widely separated 

 by a straight edge set with a row of minute dots. The passage for the foot is a deep 

 funnel-shaped cavity at the bottom of the ventral surface, covered by a loose flexible skin 

 attached to its lower, inner edge, and also to the foot. The tead is something like a 

 broad and very thick basin. Seen from above, it shows the sides as circular lobes, con- 

 nected on the dorsal side by an arched ridge. Its central hollow is small, and is laid 

 open on the ventral surface by a V-shaped gap. The edges of the gap bear stout cilia, 

 and there is a fan of similar cilia on the centre of the arched ridge connecting the 

 circular lobes. On each side of the corona, apparently on the edges of the circular 

 lobes, is a pimple bearing one or two styles. The rest of the corona is edged with 

 ordinary cilia. The foot has three feeble false joints, and two rather long and 

 sharp toes, which have the usual power of adhering to glass ; though the two dusky 

 objects running down its whole length are, I think, muscles for moving the toes, and not 

 secreting glands. The mastax has a liigli position, and the trophi are weak examples 

 of the sub-malleate type. The gastric glands are of unusual size and shape. They 

 spread out like fans up into the extreme front corners of the lorica, and appear to be thin 

 and delicately corrugated. They are joined to the apex of the stomach by long ducts. 

 Just below the mastax there are small pear-shaped, and probably glandular, bodies 

 attached by their stalks to the oesophagus. The contractile vesicle is large, and the 

 lateral canals and vibratile tags are very conspicuous ; the canals edging the lorica 

 all round down to the base of each hind spine. In the individual shown in fig. 4, 

 a narrow ovary had one ovum beginning to form near its smaller end ; and below this 

 ovum lay, in wrinkles, the empty pointed end of the ovisac. The side muscles for mov- 

 ing the head, a pair on each side, are unusually stout and obvious ; the others are much 

 as in Brachionus. A small heart-shaped nervous ganglion, with its broad end down- 

 wards, lies on the occiisut between the frontal horns ; and, seated on it, sloping down- 

 wards, is the conical sheath of the short dorsal antenna, whose tip just emerges at the 

 base of the gap in the lorica between the horns. Dr. Plate (loc. cit.) has seen two 



