[Annals N. Y. Acad. Sci., Vol. XIX, No. 9, Part II, pp. 205-224, Plates XXI- 
XXII, 2 March, 1910.] 
SOME NEW OR LITTLE KNOWN AMERICAN SPIDERS. 
By Alexander Petrunkevitch, Ph.D. 
The present article contains descriptions of a few American spiders 
belonging to two separate collections, one of which is in the American Mu¬ 
seum of Natural History and the other in my private possession. The 
genera, unless otherwise stated, conform to the definitions given to them by 
Eugene Simon in the second edition of his “ Histoire Naturelle des Araignees,” 
the only extensive work on the subject. It has been necessary to establish 
two new genera. One of these, Moenkhausiana, belongs to the f am ily 
Lycosidse and is characterized by the unusual structure of the spinnerets 
and the proportion of the legs. The other genus, Theridionexus, I place 
provisionally in the family Theridiidse, although the spider for which I have 
established this genus has many structures characteristic of Argiopidse. 
Uniform terminology is essential to a correct description of species. 
Finding the old one inadequate and confusing, I proposed a new one in an 
article entitled “ Contributions to our Knowledge of the Anatomy and Rela¬ 
tionships in Spiders,” in the Annals of the Entomological Society of America, 
Volume II, 1909. For an understanding of the principles underlying this 
terminology, I refer the reader to this article. The following abbreviations 
will be used throughout the present article: Episy named surface, EPS; 
Elyposynaxial surface, HYS; Prasymmetrical surface, PRS; Retrosym- 
metrical surface, RES. For the convenience of the reader I may state that 
the episynaxial surface in spiders is almost synonymic with dorsal; hypo- 
synaxial with ventral. In the old terminology, however, the words anterior 
and front were often used to designate the hyposynaxial surface of the first 
femora. The prosymmetrical surface corresponds to the inner surface of 
the front legs and the outer surface of the hind legs, while the retrosymmetri- 
cal surface corresponds to the outer surface of the front legs and the inner 
surface of the hind legs. In the chela', promargin stands for superior or 
anterior and retromargin for inferior or posterior. 
All measurements are given in millimeters. 
205 
