148 DR. E. BERGROTH ON STRIDULATING [May 16, 



patches are transversely stiigose in the basal part, but the striae 

 gradually become more oblique and are often practically longi- 

 tudinal at the narrow end. From the position of the patches it 

 is clear that the tibife cannot come in contact with them, and the 

 active part of the stridulatory organ must be sought for elsewhere. 

 I have found it on the inner side of the hind femur, where it 

 consists of a number of very small spinous knobs arranged either 

 in a single regular row or in two or three irregular ones. They 

 are visible under a common pocket-lens, but under a compound 

 microscope they present exactly the same structure as the tibial 

 spinules of the Tetyraria. I propose to call them " spicula 

 ^iridulatoria." The movements of the femur exactly coi'respond 

 to the different direction of the striae of the ventral patches, these 

 striae being always crossed at a right angle by the "' sjncula." By 

 rubbing the inner side of the femur over the ventral patch I have 

 experimentally produced a stiidulating noise. Stal seems to have 

 observed the " spicula stridulatorla " in Platycoris and Niarms, 

 for in his above-quoted paper of 1867 he says they have the 

 " femoribus posticis intus granulatis." In his larger work of 

 1876 he has omitted to mention it. 



In his revision of the Hemiptera Heteroptera of the British 

 Museum, Distant was apparently not satisfied with the state in 

 which he left the genus Dictyotus. He says* : " Dictyotus requires 

 revision ; all the species which Dallas included in his genus do 

 not appear to be congeneric." Without having seen Dallas's types 

 I had myself, in determining some species of this genus, come to 

 the same conclusion. In some of his specific descriptions Dallas 

 speaks of "a curved raised line on each side of the second and 

 third segments" of the venter. Walker has also described his 

 Mormidea deter sa as having the "abdomen beneath with a short 

 curved smooth line on each side near the base." I therefore 

 suspected that these particular species belong to the genus 

 Oncocoris, and this supposition has proved to be correct, my 

 friend Mr. Distant having at my request kindly le- examined the 

 types of the British authors previously referred by him to 

 Bictyotus. It is therefore necessary to give a complete revised 

 list of the species of Oncocoris, which follows here, and which is 

 essentially founded upon the communications received from 

 Mr. Distant. 



Oncocoris Mayr. 



Verb, zool.-bot. Ges. Wien, xvi. p. 362 (1866); Reise d. 

 Novara, Hem. p. 44 (1866). 



Dictyotus Dall. List Hem. Brit. Mvis. i. p. 139 (pro parte). 

 TcfAa Walk. Cat. Het. Hem. Brit. Mus. i. p. 236 (1867). 



1, Oncocoris apicalis Dall. West Australia. 



Bictyotics apicalis Dall. List, i. p. 141 (1851). 



* Ann. & Mag. Nat. Hist. (7) v. p. 388 (1900). 



