92 ANi^UAL REPORT. 



? Genus 3. Psammathi, Philippi, Archiv. fur Naturgeschicte. 

 '? Genus 4. Idomene, Philippi , " " " 



V Genus 5. Emyte, Philippi, 



GENUS 1. Cyclops. 



Bibliography. — (See Cyclops quadricornis.) 



Characters. — Cephalothorax four-jointed. Anterior antennae of the female not 



appendag-ed; of the male both greniculate. Appendage at the 



base of abdomen small. Body sub- cylindrical. Feet of the first 



pair didactyle. 



The various species of this genus are found in inland waters the world over, 



being essentially fresh water animals, in a few rases only inhabiting water a 



little brackish. They are among the most abundant of all the individuals of the 



order, every standing pool abounding in them; they are also extremely variable 



both in different stages of the same animal, in the different sexes and in different 



localities. 



The young stages of Cyclops have been named as distinct species, in so far that 

 the same animal has been honored with three or four different titles between 

 birth and maturity. In our own locality many forms have been found, and it is 

 quite likely that careful study would enable us 10 distinguish several species and 

 numerous varieties, but such is the extreme variability of the one known to exist 

 here, that it is not now possible to draw a dividing line between the varyinjgf 

 forms, so that all that is attempted is to give a general view of the species, and 

 leave further definition for more minute investigation. 



Cyclops quadricornis, Muller. 



Bibliography. — Monoculus quadricornis, Linnwus, Gmelin, Scopoli, FabricinSj 

 Jitrine, Sulzer, Donovan, Blumenbach, Manuel, Barhut, Shaw. 

 Monoculus apus. Pod a. 

 Le Monocle ^ querie fourchue, Geoffroy, 

 Le Monocle ^ quatre cornes. De Geer. 

 Cyclops quadricornis, Muller, Zool. Dan. Prod., 2416, 1776. 



Ramdhor, Latreille, Box, Lamarck, Baird, Leach, 



Koch. 



Baird, Briu. Entomost, p. 198. 



Cyclops Geoffroyi, Lamouelle, British Insects, 81. 

 Cyclops vulgaris, Desmarest, M. Edwards, Leach. 



Baird, Trans, Berw. Club, i., 97, (young). 



Garrter, Nat. Hist., Staffordshire. 



Pediculus aquaticus, Baker, Empl. for Micros. 



Satyr, Baker. 



Nauplius saltatorius, Muller, Zool. Prod., No. 2378. 



Four-horned Cyclops, Prichard, Microscop. Cab. 



Cyclops quadricornis of most recent writers. 

 The full grown female is often of considerable size, attaining the length of .09 in. 

 or more. The male is smaller, and there is every possible gradation between 

 the above and small forms scarcely perceptible to the unassisted eye. 



The cephalothorax is usually regularly oval, but varies from shoit oval to 

 oblong, it is composed of four segments, of which the anterior one is largest, 



