258 AMERICAN SPIDERS AND THEIR SPINNINGWORK. 



species. He retained my name, deeming the two spiders distinct. Not having seen a 

 European specimen, I retain the name originally given, as above, although inclined to 

 think, from study of the drawings alone, Th. radiosum and Th. gemmosum identical, or 

 perhaps the former a variety of the latter. 



CEPHALOTHORAX : Cordate, truncate and indented at the base; the summit high; the 

 head much elevated, the face projecting in front, and wide ; the fosse a slight semicircular 

 indentation ; sloping downward to the base and forward to the face ; the corselet grooves 

 distinct, as is the cephalic suture ; the color dull yellow, glossy. The sternum is cordate, 

 obtusely triangular at the apex ; color dark brown, with a broad, yellow median band ; 

 pubescent ; rounded from the sides and flat in the middle ; the labium small, scarcely more 

 than one-third the height of the maxillae, rounded at the tips ; the maxillrc as wide as, or 

 wider, than long; the tips squarely truncate, and inclined toward one another. 



EYES : (Fig. 8d.) Situated on a round, black conical projection, at the point of which 

 the midfront eyes of the ocular quad are placed ; the quad longer than wide, its greatest 

 width behind ; MF, which are considerably smaller than 31R, are separated by about 1 to 

 1.3 diameter; MR separated by scarcely more than a radius; the side eyes are separated 

 by less than a radius; white, not greatly differing in size, but MR somewhat larger; SF 

 removed from MF by a space almost equal to the area of the latter, or twice the inter- 

 vening space or more ; the clypeus is high, the margin separated from MF by 1.3 at least 

 the area of the latter ; the front row is aligned, or a very little recurved ; the rear row 

 procurved. 



LEGS: 1, 2, 4, 3; short, rather stout; scantily pubescent; provided with sharp, bristle- 

 like spines; the palps colored and armed as the legs; the mandibles long, conical, divergent 

 at the tips, glossy, yellow. 



ABDOMEN : A rounded oval ; the dorsum highly and evenly arched, almost a semicircle, 

 to the distal spinnerets ; carried by the spider in a nearly vertical position, and, therefore, 

 the base, which is rounded, towering over the cephalothorax ; the color varies from blackish 

 to yellowish brown (Figs. 8, 8b) ; the skin soft, beautifully reticulated ; the folium a some- 

 what indistinct, broad, arrowhead pattern, marked out by silvery reticulations, which give 

 the spider a shining appearance. The epigynum (Fig. 8e) is large, occupying half the width 

 of the venter, with a high, subtriangular atriolum, showing the concavity beneath ; there is 

 no scapus, simply a swelling at the middle point of the atriolum. 



MALE : (Fig. 9.) Resembles the female in color and markings ; somewhat smaller in 

 size; the palps are distinguished as shown at Figs. 9b, 9c, 9d. 



DISTRIBUTION : I have collected this species in New England (Massachusetts, Connecti- 

 cut) ; in New York, quite abundantly in the neighborhood of Philadelphia, and as far west 

 as Ohio. Dr. Marx has it from Illinois. If we accept the identity of Theridiosoma 

 gemmosum with the American species, it is widely distributed throughout Europe. 



GENUS TETRAGNATHA, WALCKENAER, 1806. 



The species of this genus are distinguished by their elongated form, the abdomen 

 being several times as long as wide. This effect is increased by the habit of the species to 

 stretch their forelegs together and lie close to the surface of plants, so that the legs and 

 abdomen form one continuous line. The cephalothorax is an elongated oval, flattened 

 upon the dorsum of the corselet; the head usually erect, wide at the face, and quadrate. 

 The Sternum is longer than wide ; and the maxillae peculiar, in that they are decidedly 

 longer than wide, concave upon the outer margin, and widened at the tip. The eyes are 

 placed in two rows, both of which are usually slightly recurved or aligned. The midfront 

 eyes are separated from one another by a space ordinarily equal to about one-half the 

 distance between the midfront and sidefront eyes ; the side eyes are nearer one another than 

 or as near as MF to MR. The mandibles are elongated, oval, usually narrower at the 

 base than at the apex ; are marked by strong teeth, and in the male are even more 



