122 GEOL. AND NAT. HIST. SURVEY OF MINNESOTA. 



Fifth foot small, one-jointed, with three spines, of which the inner 

 is large and serrate. Total length 0.8 mm., thorax 0.42 mm., abdomen 

 0.38 mm., stylet 0.09 mm., antenna 0.18 mm. Egg-sacs appressed^ 

 with few ova. 



Cyclops aequoreus Fischer. 



Plate XXIII, Fig. 5. 



Lilljeborg '53 (magniceps); Fischer '60; Brady '68, '78 and '91. 



Body compressed, attenuated caudad. Antennae shorter than first 

 segment, stout, six jointed, fourth and sixth segments longest. Fifth 

 feet with a small basal joint and a triangular lamina bearing on the 

 distal margin three spines and a seta, lateral margins ciliate. Abdo- 

 men slender, first segment very long, last very short. Stylets less 

 than twice as long as wide. Longest seta as long as the abdomen. 

 First foot with the formula 



!ex. 3 spines. - f ex. 1 spine, 



ap. 1 spine, 1 seta. Inner ramus < ap. 2 spines, 



in. 4 setse. (in. 3 setae. 



Length 0.85 mm. 



This species lives in salt marshes and brackish pools, and is inter- 

 esting for its departure from the generic type in several particulars. 



Three species of Cyclops were found by E. Pratz in 1866 in the 

 hydrant water of Munich and described as new. 



The first of these, C. emeus, is blind and colorless and has 11-jointed 

 antennse. 



The second species, G. subterraneus, is doubtfully identified by 

 Schmeil with C Mcuspidatus. 



The third, Cyclops serratus, is probably a form of C. viridis Jurine. 



Two blind species of Cyclops have been described by G. Joseph 

 ('82): C. hyalinus and C. anophihalmus, but the descriptions are not 

 accessible to me. 



HETEROGENESIS AND PREIMAGO FERTILITY IN CYCLOPS. 



The present writer's views and statements in respect to the relation 

 of sexual and anatomical maturity and the influence of the environ- 

 ment have given rise to a running criticism occupying many passages 

 throughout the recent monograph of Schmeil, '92. 



These criticisms are so inconsistent, and at times so contradictory 

 of the author's own observations and statements, that it is hopeless to 

 attempt to answer them, especially as his notions respecting varietal 

 and specific relations seem strangely obscure. If a plain statement of 

 the position of the present writer will remove any obscurity he feels 

 bound to offer it. 



