654 DESCBiPTioN OF \^Botatoria. 



destitute of spines both, in front and rear; foot and toes long and 

 slender. It forms a connecting link between Salpina and Binocha/ris. 

 The name signifying double, alludes to the gaping lorica, which forms 

 two parallel plates. 



In accordance with the tabular disposition of the family, this 

 genus follows next after Lepadella- 



DiPLAX compressa. — Form of lorica (viewed laterally) nearly a 

 parallelogram, greatly compressed. Lorica 1-1 76th. 



D. trigona. — Lorica three sided, a section forming a nearly equi- 

 lateral triangle, surface delicately punctured or stippled ; toes long 

 and slender. Lorica 1-1 60th. Leamington. 



Genus Monostxxa. The spinous-footed Rotatoria. — Eye single, cer- 

 vical ; foot simple, styEform ; lorica {testula) depressed. Numerous 

 rotatory muscles are seen in two species, and also an oesophagoal 

 head, having four muscles ; in one species the jaws are single- 

 toothed, in the other two-toothed. They have a very short oesophagus, 

 and a constricted stomach {gasterodcla), with two glands. The ovarium 

 is globular ; an ovum, with the vesicle of the germ within it, is 

 seen in two species. No male organs, vessels, nor respiratory tubes, 

 are seen. Owing to the almost constant \-ibration of the foot-like 

 tail, it is difficult to observe the true form of its termination, the 

 motion producing an optical deception : hence it appears double, 

 though in reality it is single. 



M. cornuta {Trichoda cornuta, M.) — Lorica hyaline, unarmed, and 

 truncated anteriorly. Found amongst Chara and Conferva. Length 

 l-250th. 



M. quadridentata. — Lorica yellowish, anteriorly deeply dentated, 

 resembling four horns. It is generally of a yellow leather coloiu", 

 but Ehrenberg has seen it colourless. Figs. 434 and 435 represent 

 ventral views of this animalcule ; in the latter it is extended beyond 

 its lorica, which happens when the rotatoiy ciHa are in motion. 

 Fig. 436 shews a side view, and fig. 437 the jaws and teeth sepai'ate. 

 Found in floccose matter about Conferva and the leaves of water- 

 plants. Length 1-1 20th. 



M. (?) lunaris. — Lorica hyaline, anteriorly crescent-shaped. Length 

 l-144th. 



M. hulla (Gosse.) — Body ovate, inflated, the back very gibbous; 



