42 DAVENPORT ACADEMY OF SCIENCES. 



Figure 65, Plate IX, illustrates a form which was observed in 

 the vicinity of Iowa City during the autumn of 1903. 



In many respects it differs from the description of Trachelomo- 

 nas cylbidrica, as found in Kent's " Manual of The Infusoria." 

 The lorica did not present the flattened appearance of the poste- 

 rior border and the distal margin of the tubular neck was con- 

 spicuously everted. 



The lorica was transparent, rendering visible the bright green 

 endoplasm and red pigment spot. Flagellum long. I^ength of 

 lorica, approximately, 20 microns. Habitat, fresh water. 



I refer the form to this species with much doubt as to its true 

 identity. It possibly may have been an undeveloped phase of 

 some other species of the genus. 



Trachelomonas armata Stein. 



L/orica nearly as broad as long, the surface finely punctate. A 

 series of short, sharp spines arranged in irregular rows about the 

 aperture, and frequently a number of long slender spines, curved 

 when mature, arranged around the posterior extremity. Aper- 

 ture usually in a shallow depression. Color brown. 



Length, 40 microns. 



This is the largest species of the genus observed in the state. 

 It has most frequently been found devoid of posterior spines, this 

 condition being, perhaps, a mark of immaturity. The posterior 

 spines when present have, in many forms examined, been long and 

 curved as represented by Fig. 66, PI. IX. Other individuals 

 observed possessed long, slender, but straight spines. Probably 

 full development had not been reached by these specimens when 

 examined, as Dr. T. C. Palmer reports that the curved spines are 

 late additions in the development of the organism. Usually four- 

 teen or more short, conical spines are arranged about the aperture 

 in two or three irregular rows. These are produced before the 

 posterior spines make their appearance. 



The species is widely distributed over the state, having been 

 found in many sections. It is, however, not an abundant species. 



Habitat, fresh water with algae and diatoms. 



Trachelomonas horrida Palmer. 



"Lorica ovoid, brown, the general surface tuberculate, beset 

 with long, nearly straight, prismatic, abruptly pointed spines. 



