402 



ROTIFERA. 



fibres, with ganglia, are seen in Conochilus, 

 and two red eyes are seen in both genera. 



[ Common to many. Conochilus. 

 In the less circular rotatory organ than in 

 Ptygura we see the tendency in these animals 

 to the more compound forms of that organ. 

 The lorica, in this family, is not homologous 

 with this organ in many of the other loricated 

 species ; but a case formed by a secretion 

 from the surface of the body of the animal, 

 as is seen in some Annelides, and occasionally 

 in the aquatic larva? of insects. The social 

 habit of Conochilus is very remarkable in this 

 group, as many as forty individuals being 

 frequently found together, attached by their 

 tails, and the consequence of the action of 

 their rotatory organs is a circular movement 

 of the whole mass (fig. 290.). This habit is 

 not confined to Conochilus amongst the Roti- 

 fera ; but it is interesting as connecting this 

 class in habit with the compound Polygastria 

 on the one side, and the Cirripedia and com- 

 pound Ascidia on the other. 



Fig. 290. 



The animals of Conochilus volvox, half contracted, 

 forming a circle. (After Ehrenberg.) 



Family 3. MEGALOTROCHOEA. Character. 

 Monotrochous rotatory animals, with the mar- 

 gin of the rotatory organ incised or flexuous, 

 not inclosed in a shield. 



The flexuous extended rotatory organ is 

 used for locomotion, swimming, and the sup- 

 ply of nutriment. Muscular bands are evident 

 in the interior, by which the form of the body 

 is changed. In Megalotrocha^ the alimen- 

 tary canal is supplied with a stomach, two 

 caeca, jaws with a double row of teeth, and 

 two pancreatic glands. In the other two 

 species there is a single canal, without sto- 

 mach or caeca. Microcodon has jaws with two 

 teeth. Cyphonautes is toothless. The re- 

 productive organs consist of an ovarium. 

 The ova in Megalotrocha are attached to 

 the parent by a thread. Vessels, and tre- 

 mulous gill-like organs, are observed in 

 Megalotrocha. The organs of the senses 

 are in two genera the red eyes. Mega- 

 lotrocha exhibits radiated nervous masses, 

 and above these four dark glandular bodies 

 in the neighbourhood of the mouth. These 

 have been erroneously regarded as eyes (fig. 

 291.). 



Analysis of genera. 



Eyeless. Cyphonautes. 



V.T..V /One eye. Microcodon. 



With eyes. | TwQ / yeg> Megalotrocha. 



Of these three genera, Megalotrocha is the 

 only one that is well known, or that appears 



to answer to the description of the family. 

 Cyphonautes is a marine animal, of which Eh- 

 renberg has seen but two specimens. Micro- 

 codon has also doubtful characters. Megalo- 

 trocha, of which there is only one species, M. 

 albo-fiavicans, has often been described by the 

 older observers. 



Fig. 291. 



Megalot rocha fiavicans. (After Ehrenberg.} 

 a, a, nervous ganglia ; b, jaws ; c, ovum ; d, d, 

 bodies whose functions are unknown ; e, e, e, e, trans- 

 verse vessels. 



Family 4. FLOSCULARIA. Character. 

 Monotrochous loricated Rotifers, with a ro- 

 tatory organ, with sinuous lobed or multifid 

 margins. 



The rotatory organ is divided more or less 

 deeply into two, four, five, or six divisions. 

 In the last case they may be almost said to 

 be compound. The alimentary canal gene- 

 rally exhibits a stomach, and is supplied with 

 jaws and teeth. Flosculiria has no stomach. 

 Lacinularia has two caeca. Semilunate pan- 

 creatic glands are seen in all the species. A 

 short ovarium, producing a few ova at a time, 



