some undescribed Species o/'Araneidse. 101 



Genus, Theridion, Walckenaer. 



Theridionformosum . 



Cephalothorax oval, convex, glossy, with a large indentation in the 

 medial line of the posterior region; its colour is yellowish brown tinged 

 with green, a broad black band extending along the n)iddle, and a fine 

 line of the same hue occurring on the margins. Mandibles conical, verti- 

 cal, armed with a few teeth on the inner surface, near the extremity. 

 Maxillaj inclined towards the lip, obliquely truncated at the extremity, on 

 the outer side. These parts are of a reddish brown colour, the lip, which 

 is nearly semicircular, being black at the base. Pectus heart-shaped, with 

 small prominences on the sides, opposite the legs; it is yellowish brown in 

 the middle, and has broad, black, lateral margins, which n)eet at the point. 

 Legs long, provided with hairs, of a yellowish brown colour, with reddish 

 brown bands; the firbt pair is the longest, then the fourth, which is a very 

 little longer than the second, the third pair being the shortest. Each tarsus 

 is terminated by three claws ; the two superior ones are curved and pec- 

 tinated, and the inferior one is inflected near its base. The palpi resemble 

 the legs in colour, and have a curved, pectinated claw at the extremity. 

 Eyes nearly equal in size ; four, which are intermediate, form a square, 

 the other four are disposed in pairs on the sides of the square, the eyes 

 constituting each pair being placed on a small eminence, and contiguous. 

 Abdomen oval, convex above, projecting greatly over the base of the ce- 

 phalothorax, thinly covered with hair; along the' middle of the upper |)art 

 extends a broad, dentated, dark red-brown band, bordered anteriorly with 

 I)ale yellow ; the colour of the sides is a lighter shade of red-brown ; the 

 under part is yellow, with a tinge of green, a broad, longitudinal, dark red- 

 brown band occupying the medial line. A small, pale, curved, prominent 

 process is connected with the sexual organs. Plates of the spiracles yellow. 



licngth, from the anterior part of ihc cephalothorax to the extremity of 

 the abdomen, ^th of an inch; length of the cephalothorax -rV 5 breadth 

 ^'-r; breadth of the abdomen tVj length of an anterior leg-g-V; length of 

 a leg of the third pair J. 



The male is rather smaller than the female, which it closely resembles in 

 colour ; the absolute length of its legs, however, is greater, an anterior one 

 measuring ^ths of an inch ; their relative length also is different, the se- 

 cond pair being longer than the fourth. The third and fourth joints of 

 the palpi are short; the latter, which is the stronger, projects an acute 

 apophysis from the lower extremity, underneath, and has a protuberance 

 on the outer side, from which proceed several long bristles; the fifth joint 

 is of an oblong oval shape, convex and hairy externally, concave within, 

 comprising the palpal organs ; they are moderately developed, compli- 

 cated in structure, having an obtuse projecting process in contact with the 

 protuberance on the outer side of the fourth joint, and two fine spines at 

 the lower extremity, one of which is curved into a circular form ; their co- 

 lour is dark reddish brown. The terminal joints of the palpi have their 

 convex sides directed towards each other. 



I discovered this spider on rails and gates, at Oakland, in June, 1836. 

 The structure of its snare is similar to that of the snares of the other 

 species of Theridia. 



Tribe ^ Orbitel^, Latreille. 



Genus, Epeira^ Walckenaer. 



Ejpcira niibila, 



Cephalothorax of the male inversely heart shaped, convex, glossy, with 

 a large indentation in the medial line of the [jostcrior region ; its colour 



