258 [November, 



using from it from time to time to prevent the earth getting dry or caked. Now 

 put on the earth about as much of the moss as will form a fairly compact layer 

 about an inch thick. Examine each pinnule, holding it before a bright light, and 

 only those in which a larva can be seen should be put in the glass. A piece of very 

 fine tulle or muslin should be held over the mouth of the glass by a rubber band, 

 or a piece of string. About every second or third day a few drops of the boiled 

 water on the moss will maintain sufficient humidity to prevent the pinnules drying 

 up, and consequent perishing of the larva; and pupae, but it must be watched from 

 day to day, and the first signs of fungoid growth removed. 



St. Leonard's-on-Sea : 



October, 1902. 



[This is a very interesting discovery, but Mr. Connold leaves us 

 still in doubt as to whether the moth larva is the cause of the curled 

 pinnules, or whether it only adopts those curled by a Cecidomi/ia. 

 We hope he may be able eventually to clear up this point. — Eds.] 



ON THE THORAX OF THE O ERR IB M. 

 BY DR. E. BERGROTn, C.M.Z.S. 



In describing the external anatomy of Halobrttes and Halobatodes 

 (Challenger Report, vol. vii, pt. xix) Buchanan White says (p. 29) : 

 " Below no part of the metathorax is visible," and, speaking of the 

 ventral surface of the abdomen (pp. 31, 32) : " The first segment is 

 more or less covered at the sides by the mesosternum. On the middle 

 of it is a tubercle whose apex looks backwards and downwards, and 

 is pierced by a somewhat transverse perforation. There is nothing, 

 so far as I am aware, corresponding to it in any other true insect. It 

 is possible that its homologies may be found in the ' ventral tube ' of 

 the Collembola." In the Appendix, however, the author says (p. 79) 

 that " it is possible that what we have considered to be the first 

 abdominal ventral segment may be the metasternum, though this 

 seems very improbable." 



This last interpretation is, however, doubtless the correct one, 

 and if Buchanan White had carefully compared HaJobates with the 

 other genera of the Gerridce, or if he had realized his intention to 

 work out the family monographically, he would certainly have found 

 it. The perforated tubercle is not a peculiarity of Halobates ; it is 

 typically present in the Gerridce and in the Veliadce, although in 

 many cases extremely small or hidden by the pubescence or by the 

 posterior margin of the mesosternum, and is possibly wanting in 

 the immature forms. It is verv distinct in some species of Gerris 



