INFUSORIA. 



35 



belongs are naked ; those of Codosiga and Mbnosiga are attached, while those of 

 Astrosiga and Desniarella are free-swimming. Those of the second family are loricate ; 

 Scdpingoeca and Laganceca are solitary, the one sedentary, the other free, while the 

 animals of the remaining genus, Polyoeca, are united, forming branched sujjports. 

 The thii'd family has the animalcules united by a gelatinous matter into colonies ; the 

 two genera are Phalansterium, with the collar rudimentary, and Protospongia, collar 

 well developed. 



The form represented in Fig. 29 will at once be seen to belong to Codosiga, for 

 the zooids are naked, stalked, and united 

 socially. The leading peculiarity upon 

 which the sub-order is founded is the 

 hyaline, wine-glass shaped collar, borne 

 at the upper, or anterior extremity of the 

 body. In the centre of this cup arises the 

 single flageUum, which by its motion 

 about the cup causes currents of water 

 to pass in on one side, down to the bot- 

 tom, and out on the other side ; the diseal 

 area at the bottom of the collar receives 

 the food; waste particles are also rejected 

 at this point. The collar may be with- 

 drawn into the body, and again protruded 

 at wUl. Codosiga botrytis appears to 

 have been described by Ehrenberg, under 

 the genus P^istylis of the peritrichous 

 CiUata. According to Kent it is Codo- 

 siga pulcherrima of Clark. They in- 

 crease by binary division, as shown in 

 Fig. 30. C. botrytis has also been ob- 

 served to withdraw its collar and flagel- 

 lum, and protrude rod-like pseudopodia 

 from its surface, after which a cyst formed 

 over the body contents, the latter ulti- 

 mately breaking up into sporular bodies. 

 The pseudopodal spines sometimes occur 

 before the disappearance of the collar. 

 This cosmopolitan species should be 

 looked for on aquatic plants. Mbno- 

 siga steinii is not uncommon on the stems of Epistylis plicatilis. When one of the 

 pedicles containing them is examined with a magnifying power of six hundred diameters 

 or upwards, the minute, solitary, sessile zooids of M. steinii may be seen to good advan- 

 tage. One other genus of the group can alone be mentioned ; it is Salpingoeca, of which 

 there ai-e nearly thirty species known. The animals are, if possible, more beautiful than 

 those already mentioned ; for they have, in addition to the graceful outUne of the zooid, 

 an equally graceful loiica. S. amphoridium, described by Clark, has a very wide 

 distribution; it abounds on confervae, the sessile lorica often incrusting the plants. 

 They have been seen to divide, the separated portion moving away by means of pseu- 

 podia ; in this condition it has the appearance of Amoeba radiosa. After a time it 



Fig. 29. — Codosiga botrytis, greatly enlarged.' 



