56 FRESHWATER RHIZOPODS OF NORTH AMERICA. 



under observation was alive only by seeing the usual changes of the con- 

 tractile vesicle. Otherwise the animal appeared motionless, although close 

 watching would lead to the detection of an exceedingly slow change in the 

 wrinkling of the surface 



From the inactive character of Amoeba verrucosa, and the frequent 

 comparative deficiency of food in the endosarc, I have suspected that the 

 animal might express an exhausted state of Amoeba proteus. 



One of the most common and well marked amoeboid forms, represented 

 in figs. 12-18, pi. Ill, was originally described by Mr. Carter under the 

 name of Amoeba quadrilineata. Of all the varieties or species of the genus 

 it is that which at any time I have been able to find with most certainty. 

 I have frequently observed it in association with other named forms, espe- 

 cially Amoeba radiosa and A. verrucosa. I have also repeatedly noticed 

 intermediate forms, which have led me to view A. quadrilineata as the 

 young of A. verrucosa. It was not until after this determination, in 

 examining the literature of the subject, that I learned Mr. Carter had 

 arrived at the same conclusion from a different point of view. In an article 

 "On the Freshwater Infusoria of Bombay" (An. Mag. Nat. Hist. 1857, xx, 

 page 37), he remarks: "I have also met with another species of Amoeba 

 undergoing ovular development, viz. A. verrucosa, Ehr., precisely like that 

 which I have already described ; the Amoeba perishing as the ovules are 

 developed and ending in becoming a mere ovisac." He adds: "This Amoeba 

 appears to me — for I have watched the development of a group for many 

 months together — to be the adult of my A. quadrilineata, and therefore the 

 latter is not a new species. The formation and development of the ovules 

 took place in April, and the organism appears to require at least nine 

 months to come to maturity." 



The young of Amoeba verrucosa, figs. 12-27, as ordinarily seen, appears 

 as a small hyaline pyriform body, usually actively moving, with the broader 

 extremity in advance The clear ectosarc forms a thick or broad expanse 

 in front, gradually thinning away posteriorly to a narrow border. It is 

 remarkable for retaining persistently fixed, in nearly the same relative 

 position, four equidistant narrow longitudinal folds or doubly contoured 

 lines. These extend from the back end of the animal, but do not reach its 

 front, ceasing shortly in advance of the visible mass of endosarc. The 

 latter is pale granular, and it extends from the posterior extremity ordinarily 

 about three-fourths to four-fifths the extent of the animal. 



