i8 
Poisonous Arthropods 
color and are distinctly in front of the middle of the thorax, the 
lateral eyes of each side widely separate. The tarsi of the fourth 
pair of legs has a number of curved setae in a single series. It has on 
the ventral side of its abdomen an hour-glass shaped spot. The full- 
grown female is about half an inch in length. Its globose abdomen is 
usually marked with one or more red spots dorsally along the middle 
line. The male is about half as long but has in addition to the dorsal 
spots, four pairs of stripes along the sides. Immature females 
resemble the male in coloring (fig. 9). 
Regarding the distribution of Latrodectus mactans, Comstock 
states that: “Although it is essentially a Southern species, it occurs 
in Indiana, Ohio, Pennsylvania, New Hampshire, and doubtless other 
of the Northern States.” L. geometricus has been reported from 
California. 
Other Venomous Spiders —While conclusive evidence regarding 
the venomous nature of spiders is meager and relates almost wholly 
to that of the genus Latrodectus, the group is a large one and we are 
not justified in dismissing arbitrarily, all accounts of injury from their 
bites. Several species stand out as especially needing more detailed 
investigation. 
Chiracanthium nutrix is a common European species of the family 
Clubionidse, concerning which there is much conflicting testimony. 
Among the reports are two by distinguished scientists whose accounts 
of personal experiences cannot be ignored. A. Forel allowed a spider 
of this species to bite him and not only was the pain extreme, but the 
general symptoms were so severe that he had to be helped to his 
house. The distinguished arachnologist, Bertkau reports that he, 
himself, was bitten and that an extreme, burning pain spread almost 
instantaneously over the arm and into the breast. There were slight 
chills the same day and throbbing pain at the wound lasted for days. 
While this particular species is not found in the United States, there 
are two other representatives of the genus and it is possible that they 
possess the same properties. We are unaware of any direct experi¬ 
mental work on the poison. 
Epeira diadema, of Europe, belongs to a wholly different group, 
that of the orb-weavers, but has long been reputed venomous. Robert 
was able to prepare from it an extract whose effects were very similar 
to that prepared from Latrodectus, though feebler in its action. Under 
ordinary circumstances this spider is unable to pierce the skin of man 
