The Mastigophora 175 



Six families may be assigned to the order: Codosigidae, Phalansteriidae, 

 Trypanosomidae, Cryptobiidae, Amphimonadidae, and Bodonidae. 



Family 1. Codosigidae. This group (30, 181) includes species with a 

 "collar" (Fig. 4. 40). As described in Codosiga (Fig. 4. 40, K), this collar 

 is a protoplasmic membrane which can be extended as a hollow cone 

 surroimding the basal portion of the flagellum (176). The collar can be 

 retracted completely. The body is enclosed in a thin "mucous envelope" 

 apparently continuous with the stalk. During feeding, the anterior end 

 of the body contracts away from the envelope and food particles, driven 

 by flagellar currents, drop into this space. As the body surges back against 

 the envelope, the food particles apparently are forced into the body. The 

 expanded collar evidently directs food into the space between the body 

 and the envelope. Many choanoflagellates resemble the choanocytes of 

 sponges to such a degree that Kent (130) included them with the sponges 

 in his order "Choano-flagellata." The similarity may involve not only 

 the collar but also a parabasal body, or apical body (Fig. 1. 10, L, M). A 

 single flagellum is characteristic. An interesting feature of the sessile 

 Codosiga botrytis is that flagellates which become detached swim stalk- 

 first (176). Both solitary and colonial forms are known. In addition, tem- 

 porary clusters of several flagellates, failing to separate after fission, may 

 remain attached to a stalk, as in Codosiga (176). 



The family includes several genera of naked flagellates — Codoiiosigopsis Senn (Fig. 

 4. 40, H); Codosiga James-Clark (Fig. 4. 40, K); Desmarella Kent (174; Fig. 4. 40, C); 

 Diplosiga Frenzel (Fig. 4. 40, I); and Monosiga Kent (245; Fig. 4. 40. J). A lorica is 

 present in several others: Diplosigopsis France (Fig. 4. 40, E); Lagenoeca Kent (Fig. 

 4. 40, D); and Salpingoeca James-Clark (Fig. 4. 40, A). Spheroid colonies are developed 

 in Protospongia Kent (Fig. 4. 40, G) and Sphaeroeca Lauterborn (Fig. 4. 40, F). 



Poteriodendron Stein and Histiona Voigt, sometimes grouped with the choanoflagel- 

 lates, probably are Chrysomonadida (93. 224). This is also the case for Bicoeca James- 

 Clark (222). 



Family 2. Phalansteriidae. Little is known about Phalansterium Cien- 

 kowski (181; Fig. 1. 3, A), although the presence of a simple collar 

 closely fitting the flagellum suggests a relationship to the Codosigidae. 

 The genus includes both branching and spheroid or discoid colonies 

 with a granular matrix. 



Family 3. Trypanosomidae. These parasites have a single flagellum 

 ending in a blepharoplast, near which lies a spheroid or discoid kineto- 

 plast (Fig. 1. 10, J, K). The flagellum may or may not form part of an 

 undulating membrane. Life-cycles are dimorphic or polymorphic. Four 

 different types (Fig. 4. 41) occur in the family — the leishmanial, lepto- 

 monad, crithidial, and trypanosomal forms. In invertebrate hosts, the 

 flagellates are often attached to the lining of the digestive tract or to 

 other surfaces, Such stages are sometimes referred to as haptomonads; 



