Spiders of the Genus Latrodectus 17 



Kobert concludes that in its chemical nature the poison is neither 

 an alkaloid, nor a glycoside, nor an acid, but a toxalbumen, or poison- 

 ous enzyme which is very similar to certain other animal poisons, 

 notably that of the scorpion. 



9. Latrodectus mactans; (a) female, x 3; (&) venter of female; (c) dorsum of male. 

 After Comstock. 



The genus Latrodectus is represented in the United States by at 

 least two species, L. mactans and L. geometricus. Concerning L. 

 mactans there are very circumstantial accounts of serious injury and 

 even death in man*. Latrodectus mactans is coal black, marked with 

 red or yellow or both. It has eight eyes, which are dissimilar in 



*Dr. E. H. Coleman (Kellogg, 1915) has demonstrated its virulence by a series 

 of experiments comparable with those of Kobert. 



