1919] Kofoid-Swcztj: Lcidt/opsis sphaeric-a 111 



In view of the taxonomie importance attached to the numl>er of 

 flagella in other orders of the Flagellata, where these organelles serve 

 as the chief features of classificatory value, these differences in their 

 flagellar coating seem to create a generic distinction between the two 

 forms and not a specific one only. We have therefore proposed a new 

 genus in the order of Trichonymphidae for tliis form with the follow- 

 ing characters: 



Leidyopsis gen. nov. : Trichonymphidae with ectoplasmie differen- 

 tiations found only on the anterior third of the body, the remainder 

 of which is covered with a thin pellicle; neuromotor system consisting 

 of one anterior group of long flagella, oblique fibers, longitudinal 

 myonemes, basal granules and centroblepharoplast. One species only, 

 the tj-pe, Leidyopsis sphaerica sp. nov. from intestine of Tcrmopsis 

 angusticoUis Walker from Berkelej', California. 



SUMMARY 



1. Leidyopsis sphaerica is a flagellate of the Trichonympha type, 

 witli the same structural characteristics but with a lower type of 

 evolutionary development. 



2. It is characterized by the presence of a neuromotor system 

 consisting of a highly developed centroblepharoplast, oblique fibers, 

 basal granules and related flagella, restricted to a single anterior 

 zone, a differentiated ectoplasm on the anterior third of the body, 

 surface ridges from the crests of which spring the flagella, and an 

 alveolar layer. Longitudinal myonemes are found in the endoplasm. 



3. The nucleus is anterior in position and is distinguished by the 

 presence of a heterochromosome contained within a small vesicle. 



4. Nutrition is holozoic but its methods of feeding are unknown. 



5. Division is of the trichonymphid type. The centroblepharo- 

 plast, with its connecting motor organelles and ectoplasmie structures, 

 divides longitudinally with the formation of an extra-nuclear parjt- 

 desmose between them as the two parts separate. 



6. Division of the chromosomes is longitudinal, and takes place 

 prior to the appearance of division in other structui'es of the body. 

 About forty-eight chromosomes are formed. This number is reduced 

 in pseudosynapsis to twenty-four. 



7. The nuclear membrane remains intact throughout mitosis, with 

 the spindle fibers arising from the ends of the paradesmose and centro- 

 blepharoplast and passing through it. 



