52 THE ROTIFERA. 



singular ; resembling very fine lace. Two low ridges run from its posterior dorsal edge, 

 on either side of the median line, to the projecting spines ; and, from the central strip 

 contained between them, the lorica slopes rapidly to the edge of the ventral plate. 

 There are faint traces of large tessellations along these two ridges. The foot is remark- 

 able ; for it has the false joints of a Noteus and, near the base, the usual transverse 

 wrinkling of a Brachionus : the toes, too, are not only unusually long, but are them- 

 selves retractile like those of a Philodina. 



Length (of lorica), -^V ^J -rhv inch. Habitat. A pond in Epping Forest (Rousselet). 



Brachionus militabis, Elirenhenj (42), (PL XXXIV. fig. 2:-5). 



Bracliionns conium Atwood (2). 



SP. CH. Lorica tessellated, both surfaces covered icith raised points ; ten spines in 

 front, of luhich four are on the dorsal margin, four on the ventral, and two where the 

 margins meet ; also four sjnnes behind, the middle pair {between which the foot issues) 

 being of marked imequal length. 



Ehrenberg says tiiat jnilitaris has a rough lorica, and no fewer than twelve spines 

 in front ; but Colin [loc. cit.) describes it as tessellated, and as having only ten spines in 

 front.' Curiously enough, of the two figures in which Ehrenberg appears to intend to show 

 all the spines, one has only ten spines in front, and the other eleven. Cohn's figures 

 make the lorica distinctly unsymmetrical throughout, a feature almost lost in those of 

 Ehrenberg. The two middle front dorsal spines are longer than any of the other 

 anterior ones ; they are generally curved downwards, and are not unfrequently twisted 

 awry ; Mr. Atwood's figure (loc. cit.) shows them bent, half way up, at right angles to 

 their usual direction. The posterior, unequal pair, which guard the exit of the foot, have 

 the right hand spine (dorsal view) much the longer of the two ; and the outer posterior 

 pair, at the angles of the lorica, are also of unequal length. 



This Eotiferon has a very large contractile vesicle; which, according to Colin, occu- 

 pies, when fully expanded, two-thirds of the body-cavity. He also describes it as con- 

 sisting of two chambers,- and states that, on mixing a little indigo in the water, he has 

 seen fine particles of the pigment drawn up through the cloaca into the contractile 

 vesicle, and again expelled from it over the same path. 



Mr. D. Bryce, who found this Brachionus lately near London, says, " the foot-orifice 

 seems to be twisted on one side, so that the spines bounding it are in different planes ; 

 the left-hand and smaller spine being altogether deiwessed below the right-hand one, 

 and pointing slightly downwards. The solitary dorsal antenna is moderately stout, and 

 furnished with very distinct long setse ; but I could not make out the paired lateral 

 antennfe. The eye is large, and situated at the hinder end of a large brain. The gas- 

 tric glands are triangular. The animal is fond of rotating, in one spot, round its longer 

 axis, just like Syncliata tremula, though I could see no trace of an anchoring ' cable.' " 



Length (of lorica), from -,|o to y^^ inch (D. Bryce). Habitat. ]3erlin (Ehrenberg) ; 

 near London (D. Bryce) ; Queensland (V. G. Thorpe) ; Philadelphia, U.S. (Leidy). 



Brachionus polyacanthus, Ehrenberg (42), (PI. XXXIV. fig. 24). 



SP. CH. Lorica smooth; with four long occipital spines ; tltc pectoral margin six- 

 toothed ; posterior spines five, the two outer of which are very long. 



' Mr. V. Gimsoii Thorpe, Surgeon, E.N., and Mr. D. Bryce have obliged me with characteristic 

 drawings, which they have made, of specimens found by the former at Brisbane, and by the latter near 

 London. Each of these observers figures the tessellations, the ten anterior spines, and the general lack 

 of symmetry of the lorica. Professor Leidy also has favoured me with an excellent drawing of the 

 dorsal surface from an American specimen. 



■' The contractile vesicles of Axiilanckna Ebhcsbornii, of Scaridium cv ^nciijlotum, and of other 

 Rotifera, have also this chambered appearance ; which is due to the constriction of the surface by very 

 fine muscular threads. 



