On the Development vf the Sexes in Insects. 205 



oi Rhynchonellaj &c., and concluding with the following pas- 

 sage : — 



" But let me not forget to acknowledge that I was in error 

 in doubting the absence of perforations ^ in any Brachiopod 

 whatever:' the account which Dr. Carpenter has given of 

 Rhynchonella psittacea in his late chapter* is quite conclusive 

 on this point ; but I cannot help thinking, from their occurring 

 in ^.? (jfein{tz{ana'\j that perforations will yet be found in 

 congeneric species supposed, or stated, to be without them" J. 



The way Dr. Carpenter writes with reference to my volun- 

 tarily acknowledged error, also the other " remarks " he has 

 indulged in in his letter, will, I feel assured, be quite sufficient 

 to convince the " scientific world " that, for anything more he 

 can adduce, the " main question " {{. e. the " remarkable fact 

 incontestably established ") at issue between us is, as far as 

 we are mutually concerned, now closed, — ^that, if kept open, it 

 would inevitably degenerate into a mere personal dispute, 

 redundant of reticences, and bolstered up with no end of 



irrelevant matter. v j. ^ q 



lours very truly, &c. 



William King. 



XXI. — On the Law of Development of the Sexes in Insects. 

 By Professor YoN Siebold§. 

 The assertion made by Landois in his preliminary communi- 

 cation Ij that the eggs laid by insects possess no definite traces 

 of the sexual organs, and that the sex of the larvas is only 

 developed as male and female after their escape from the egg- 

 shell by the influence of difference of food received from with- 

 out, will not only possess the highest interest for all naturalists 

 who attend to the reproductive history of organic bodies, but, 

 as Landois applies this theory specially to the reproduction of 



* Reference is here made to Dr. Carpenter's memoir " On the Intimate 

 Structure of the Shells of Brachiopoda," appended to Mr. Davidson's 

 Monograph of Brit. Foss. Brachiopoda : Introduction. A perusal of my 

 footnote will explain the reason why I only refen*ed to Dr. Carpenter's 

 "late chapter." 



t The presence of perforations in this species has caused me to regard 

 it as the type of a new genus (Rhynchopm-a) of the family Rhynchonellidae. 



X See Ann. & Mag. Nat. Hist. ser. 2. vol. xvii. p. 337. Even in June 

 (Geological Magazine) of last year I again drew attention to this point, 

 acknowledging " the mistake I made in asserting that certain imperforate 

 Palliobranchs are perforated," and in " concluding that all Spiriferidae are 

 perforated." 



§ Translated by W. S. Dallas, F.L.S., from the Zeitschrift fiir wis- 

 sensch. Zoologie, Band xvii. pp. 525-532. 



51 See Zeitschrift fiir wiss. Zool. xvii. p. 375, and Ann. & Mag. N. H. 

 ser. 3. vol. xix. p. 224. 



Ann. & Mag. N. Hist. Ser. 4. Vol.n. 15 



