8 CONNECTICUT GEOL. AND NAT. HIST. SURVEY. [Bull. 



found. In the study of Protozoa careful figures are always 

 of more value to the microscopist than specific descriptions, 

 because of the difiiculty in studying the animals and tracing 

 out minute details. It frequently happens that one can easily 

 recognize a species from its appearance, when it would be 

 impossible to determine the characters upon which the species 

 or even the genus is based. In the study of a rapidly moving 

 microscopic animal it is often impossible to make out minute 

 details, and points in internal structure, like the nucleus 

 and vacuoles cannot, in many cases, be decided upon in the 

 living specimens. In all such cases the general appearance 

 of the animals is of more use in determination than specific 

 descriptions. For this reason there is given, in the present 

 report, a figure of every species of animal thus far thoroughly 

 identified, and, in some cases, two or three figures of the same 

 type are given where specimens show considerable variations 

 from each other. The figures are all original, and drawn by 

 the author from the actual specimens. 



The key printed in this preliminary report is designed for 

 the use of working students, and Is not intended to indicate any 

 real relations of the organisms in question. The problem of 

 the general relations of the groups will be discussed when a 

 more complete report of the Protozoa may be prepared. This 

 key is based upon one which has been found most useful to the 

 author, namely, the one published by Kirchner and Bloch- 

 mann.* The key, as printed in the following pages, follows 

 in general the one devised by these authors. It has, how- 

 ever, been much modified, to make it clearer and more useful 

 to a beginner. Inasmuch as quite a number of genera are 

 clearh- present in our waters which are not included in the 

 above-mentioned key, it has been found necessary to add these 

 new genera to the key. It is believed, therefore, that our key 

 is an improvement over any before published. This key in- 

 cludes all the genera known to occur in fresh water, whether 

 they have yet been detected in Connecticut or not, and, conse- 

 quently, all that are likely to be found in our State. 



* Die Mikroskopische Pflanzen- und Thierwelt des Susswassers, Braun- 

 schweig, 1886. 



