Mr. J. Blackwall on some species of Araneidea. 299 



My son, John Blackwall, discovered this spider in an outbuild- 

 ing at Oakland in June 1845. 



2. Thomisus pallidus. 



Length of the female ££ths of an inch ; length of the cephalo- 

 thorax y 1 ^ ; breadth TT ; breadth of the abdomen j- ; length of a 

 leg of the second pair \ ; length of a leg of the third pair / n . 



Mandibles short, strong, subconical, vertical, furnished with 

 some erect bristles in front, towards the inner side : maxillae 

 slender, convex near the base, pointed at the extremity, and in- 

 clined towards the lip, which is triangular : sternum heart-shaped : 

 legs provided with short hairs and strong spines ; the first and 

 second pairs are very decidedly longer and more robust than the 

 third and fourth pairs, the second pair being rather the longest 

 and the third pair the shortest : palpi short, provided with hairs 

 and spines : these parts are of a pale yellowish brown colour, the 

 lip being somewhat the darkest. Each tarsus is terminated by 

 two curved, pectinated claws, and the palpi have a small, curved, 

 pectinated claw at their extremity. Cephalo-thorax convex, 

 compressed before, broadly rounded in front, depressed on the 

 sides and at the posterior extremity, without any indentation 

 in the medial line ; there is a row of strong bristles directed for- 

 wards on the frontal margin, and its colour is yellowish brown, 

 palest on the lateral margins, with an obscure, longitudinal, red- 

 dish brown band directed backwards from each lateral pair of 

 eyes. Eyes disposed on the anterior part of the cephalo-thorax 

 in two curved rows, forming a crescent whose convex side is in 

 front ; the lateral eyes, which are seated on a protuberance, are 

 much larger than the intermediate ones, those of the anterior 

 row being the largest of the eight. Abdomen depressed, corru- 

 gated, much broader at the posterior than at the anterior extre- 

 mity, the latter, which appears as if cut in a straight line across, 

 projecting over the base of the cephalo-thorax; it is sparingly 

 supplied with short strong hairs, and is of a pale yellowish brown 

 colour ; on the upper part are five conspicuous circular depres- 

 sions ; the three anterior ones form a triangle whose vertex is 

 directed forwards, and the other two are situated parallel to its 

 base. Sexual organs red-brown. Plates of the spiracles pale 

 yellow. 



Found among grass in a pasture at Oakland in September 

 1845. 



This species, like Thomisus cristatus, Thomisus bifasciatus, 

 and some others, has the power of changing the colour of the 

 anterior intermediate pair of eyes from dark red-brown to pale 

 golden yellow by a very perceptible internal motion. No such 



