; 
ENTOMOSTRAOA OF MINNESOTA. 
2 ik Ame tht ng as al ite ES a car, TDA SL! Pcl iy’ 
211 
The males have the opening of the vasa deferentia in front of the 
claws, which may be absent; the antennules are also modified, being 
longer and curved. Jn Lathonura the abdomen is elongated posteriorly 
till it begins to suggest a transition to Polyphemus. 
The known genera and their distribution is as indicated below. 
Half of the known species are found in America, one-fourth being 
peculiar to it. 
i 
a 
| a 
Gusena. Number of| Eoropean, | 4,400, | Onlin) Total 
Species. 4 
NIRCPOUNTLR cncc uaunete desis csvesscteneant 4 3 2 1 3 
SUM OTULTaasenceels oa ceseece cites oo ubiaw nes 1 1 MAY A iteredaceeeites 1 | 
MO PAMOUNTER ce ciseosee en sveodoess Sees 1 RTE Wi Ree set ven seeeall ot aac cone recalerece ame eeeem : 
IME LOCELAS i aatce asst cdadenvce cal sense il Glee Weep a asic cle oan ell eaite asl bake esateeeeeneee § 
IA CAMUNOLEDETIS:. vseesseuel seeaenesees« 1 Re) Se) wate, Lag cella senavaee eee lceoe meced metee 
Ouiny Oma sitar «Rees siiate scewsenseacines s¢au'e 1 i dra ene ceeerstige 1 
iy WEG Map uitde:e sc). tear ercscwene<o sey BRS SO ast coegate tes acinus uacinat 1 1 
GEV PEUSt sss. iavembensessaccses seems: 3 Poa | Seen 1 i 
ARG Gals: Mica eee pee cence peau scutes 13 10 | 4 3 7 
GENUS MACROTHRIX Baird. 
Body oval, pointed behind; head broad; antenne of first pair long, 
nearly straight, beset with spines, olfactory threads terminal; swim- 
ming antenne large and powerful, propelling the animal by bounds; 
three-jointed ramus with a greatly elongated sete which is thorned 
and jointed; labrum with the basal joint enlarged, resembling that of 
Iynceids; first foot with a hook in both sexes; last foot with a long 
process (respiratory body); abdomen short; claws short; caudal stylets 
often with a bush of hairs at tip. The intestine is straight and without 
ceca in front or behind. 
The first one to observe a member of this genus, apparently, was 
O. F. Miller whose Daphnia curvirostris is usually referred to Macro- 
thria laticornis. 
The name EHchinisca was proposed by Lievin, but Macrothrix was 
applied by Baird in 1843. Four species are known, three of which 
occur in America, and without doubt the fourth will ultimately be 
found. No males of this genus were known till 1877 when the male 
of M. laticornis was described and figured (Grube and Weismann ’80.) 
Nearly two years later the male of MW. rosea was described from Wis- 
consin by EK. A. Birge. Descriptions of the male of Lathonura are also 
given in both the above mentioned sources. 
14 
