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



As very strong evidence of our observation of the occurrence of 

 sexual adults with larval characters may be noted a statement of 

 Schmeil himself, who nevertheless seems to be so given to his theory 

 as to be quite unable to see its bearing. He says: "Nicht unerwahnt 

 soil bleibeu, dass zwischen den exemplaren dieser art, welche den 

 Tiimpeln des Brockeugipfels entstammten, sich eine Aozahl Miinnchen 

 vorfanden, bei welchen samtliche Aeste der Schwimmfiisse aus je drei 

 Segmenten bestanden. Dieser Fall ist desshalb besonders iuteressant, 

 well hier ein Fortschreiten nach Vervollkommnung im Korperbau 

 eines Tieres direct zu konstantiren ist." The writer is obliged ta 

 confess that he cannot understand why it is not more natural to regard 

 the two-jointed condition (which is common to all larv;e) as a retarded 

 or atavistic state, from which the species tends to escape toward the 

 norm under favorable condition, than to postulate an exceptional 

 specific norm (which in this case is confessedly unstable), and assume 

 that from some cause, utterly unknown to us, the form tends to ''pro- 

 ceed to a greater completeness in structure.'' The "greater comple- 

 tion" or realizing of its ideal — "Vervollkommnung" — implies that it 

 is incomplete or has failed to attain its specific possibilities, unless, 

 indeed, the generic characters have for Schmeil a sort of metaphysical 

 cogency or power over its members apart from its heredity. The same 

 considerations apply to the antennae. The fifth feet are as in (J. hicus- 

 pidatus. The form of the receptaculum is much relied on to differen- 

 tiate this form, but is admitted to vary within wide limits. Length 

 0.86 to 1.1 ram. Motions slow. 



* Cyclops moclestus Herrick. 



Plate XXI, Figs, 1-5. 



Herrick '83 and '84; Marsh '92. 



This small species, 1.0 mm. long, was first recognized in Cullman 

 county, Ala., but occurs also in our lakes. The color varies, but very 

 characteristic is the peculiar shining or glaucous surface of th& 

 strongly arched thoracic shield and the evenly curved segments of the 

 abdomen. The antennse reach but little beyond the very long first 

 segment; they are usually 16 jointed, but I have notes of a similar form 

 in which the antenniie are ITjointed. The feet are all three-jointed 

 and armed as follows: 



First Foot. 

 ex. 3 spines. ( ex. 1 seta. 



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



in. 3 setaj. (.in. 2 setie 



Second Foot. 



ex. 3 spines. Tex. 1 seta. 



Outer ramus -{ ap. 1 spine, 1 seta. Inner ramus < ap. 2 spines. 



4 setae. ( in. 1 spine, 2 setse. 



