 BULLETIN OF THE UNITED STATES FISH COMMISSION. 243 



the lower end of whicli is dilated into a globular space by the force of 

 the currents produced by the cilia, in wliich the i^articles of food are 

 rotating- in the contained water. This space enlarges gradually until 

 eventually its connection with the throat is suddenly broken by a col- 

 lapse of the walls which join the globular space with the former. In 

 this way food-vesicle after food-vesicle is taken into the body of the 

 animalcule, from which the creature will abstract whatever is useful and 

 cast out near the mouth whatever is contained in the food-vesicles that 

 is indigestible. The writer has seen the process in a number of forms, 

 and it is not unusual to observe a dozen or more food-vesicles in the 

 body of a single protozoan. Many parasitic forms, however, are* mouth- 

 less, such as Opalina, Benedenia, Pyrsonympliaj Trichonym2)ha, &c., where 

 the nourishment is probably obtained from their hosts by transudation 

 through the body-walls. In other forms again comparatively large 

 objects are swallowed with apparent ease, judging from shells of other 

 protozoan tyi^es which are found within their bodies. Such a form I 

 encountered in a slightly brackish water-pool near New Point Comfort, 

 Virginia, during the summer of 1880. It was apparently a very large 

 species of Prorodon of an irregular cylindrical form which had in a 

 number of instances swallowed five or six large difflugians, Arcella vul- 

 garis, the shells of which remained within the animal to testify to the 

 nature of the food it had been devouring. Some other mode of swal- 

 lowing such large prey is probably practiced by this large ciliate, very 

 different from the method first described. In the same pool a very pe- 

 culiar form of hyi)Otrichous iufusorian was detected, which was clearly 

 very nearly allied to Chilodon cuctdlulus of Elirenberg, but the dorsal, 

 non-ciliated side of its body was not gently rounded, but flat with a 

 prominent crenate rim surrounding it -, from this peculiarity it may be 

 called Chilodon corona f vs. 



The mode of swallowing their food adopted by the fresh-water rhizo- 

 pods has been elaborately described in a few instances by Professor 

 Leidy in his splendid monograph of this grouj), published by the Geo- 

 logical Survey of the Territories. Their food appears to be mainly veg- 

 etable, and consists, for the most part, of diatoms and desmids, though 

 a ciliated protozoan or rhizopod was occasionally met with in the body 

 of AviKha. The marine rhizopods appear to be herbivorous as well as 

 carnivorous, remains of both Protophytes and Protozoa having been de- 

 tected in their bodies. Vampyrella has been described as almost para- 

 sitic upon the clustered frustules of Gomplionema. 



Some aberrant ciliated forms, like the Gastrotricha and Coleps, are 

 somewhat peculiar in their organization, and we know little of their 

 feeding habits. 



The Suctoria or Tentaculifera, which are abundant in some places, 

 both in fresh and salt water, appear to be indiscriminately herbivorous, 

 as well as carnivorous. In fresh water I have met with them infesting 

 the back of the common water leech, Clepsine^ the species being appar- 



