=e . } J 
106 GEOL. AND NAT. HIST. SURVEY OF MINNESOTA. 
ex. 2 spines. (ex. 1 seta. 
Outer ramus 4 ap. 1 spine, 1 seta, Inner ramus 4 ap. 2 spines. 
in. 4 spines. in. 2 sete. 
The spines are serrulate and the sete very plumose. Fifth foot 
two-jointed, basal joint longer than wide, with a series of small teeth 
and a long seta, apical joint with three plumose sete. Color bluish 
or banded, the antennz especially banded on the fifth to sixth and — 
twelfth to fourteenth joints. 
* Cyclops signatus var. coronatus. 
PLATE XV, Fies. 1-4. 
First segment of thorax long, its length to that of the entire thorax 
about as 1: 1.50. Last segment of antenne with the proximal portion 
of its hyaline plate coarsely serrate. Caudal stylets short, ciliated 
internally, length to width as 1.25:1. Second segment of antennules 
short. Inner apical seta of stylets one-third longer. Color marked. 
* Cyclops signatus var. tenuicornis. 
PLATES XV, Fias. 5-7; XX, Fries. 1-7; XX XIII, Fras. de 
First segment of thorax shorter, its length to that of the entire 
thorax as1:1.9. Last segment of antenne with unserrated lamella. 
Caudal stylets longer, length to width as 2.1:1, inner aspect not 
ciliated. Outer apical seta half as long as inner. Second segment of 
antennules longer. Color variable but always banded or splotched. 
It is also generally true that the ovisacs in the present variety are 
more strongly divaricate than in the variety coronatus. 
Schmeil also finds differences in the form of the receptaculum and 
sexual elements. 
Over against the above differences must be set the close agreement 
in the armature of the feet and the fact that the late stages of coronatus 
remain to be described while it is always associated with C. tenuicornis, 
generally in greater numbers. The greater hairiness and stronger 
serrations of ©. coronatus are characters suggestive of advanced age, 
as has been observed in other species. C. tenwicornis is frequently 
found without C. coronatus, but the reverse has not been found true in 
our experience. Finally attempts at experimental rearing of coronatus 
from tenuicornis have been made, and, while some possible sources of 
error unfortunately crept in, yet I am morally conyancrd that the ap- 
parent transformation was genuine. 
Dr. Schmeil discusses this question at length without adding any- 
thing to the evidence. He adduces the differences in structure, 
though he fails to find anything but such as consist in altered pro- 
portions of structures common to both. He claims that embryos of 
