igii,] Miscellanea. 229 



In Chaoborus, lyichtenstein, must certainly be placed the follow- 

 ing : plumicornis , F., pallida, F., fusca, St2ieg. , flavicans , Mg., mani- 

 lensis, Sch., punctipennis , Say,, the latter with trivittata, Lw., as a 

 synonym. 



Prof. Kertesz's catalogue gives the following species under 

 ' ' Corethra ' ' and there are no means to hand of testing their true 

 generic position, but the probability is that the majority, perhaps 

 all of them, belong to Chaoborus. It may be noted that the above- 

 mentioned catalogue uses the term Corethra to embrace the species 

 now certainly referred to Chaoborus as well as the following ones of 

 uncertain position: antarctica, Huds. (New Zealand), nyblaei, Zett. 

 (North Europe), obscuripes, Wulp (Central Europe), pilipes, Gimm 

 (Eastern Europe), and rufa, Zett. (North Europe). 



E. Brunetti. 



CRUSTACEA. 



On the distribution of the different forms of the 

 GENUS Ibla. — Until a few years ago only two forms of the genus 

 Ibla (I. quadrivalvis (Cuvier) and 7. cummingi, Darwin) had been 

 described, but in 1907 Hoek described a third under the name 

 Ibla sibogae {Siboga-Exped., Mon. xxxia — Cirripedia Pedunculata — 

 p. 48, pi. iv, figs. 20 — 22, pi. V, figs. I — 8, 1907). The most 

 curious difference between I. quadrivalvis and I. cummingi is, 

 as Darwin pointed out, the fact that whereas the large indivi- 

 duals of the former are hermaphrodite and possess a well- 

 developed penis, similar individuals of the latter are exclusively 

 female and possess no penis {Mon. Cirripedia — lyCpadidae, p. 204). 

 The typical form of I. cummingi can be readily distinguished on 

 superficial examination by blue markings on its valves which 

 are quite absent from those of /. quadrivalvis. All other differ- 

 ences are trivial and, in my opinion, fall well within the limits 

 of individual variation. /. sibogae (except for minute structural 

 differences which I also consider of little importance) differs from 

 I. cummingi , with which its sexual features are in agreement, in the 

 absence of the blue markings; h om. I . quadrivalvis it c2in]\Q.r&\Y 

 be distinguished unless the animal be dissected out of its shell. 



I have recently obtained cotypes or paratypes of I. sibogae 

 and have examined considerable numbers of specimens of the genus 

 from the Gulf of Oman, the coast of Burma, the Straits of 

 Malacca, the Gulf of Siam, Port Jackson and New Zealand. 

 With the exception of those from Australia and New Zealand, 

 these specimens agree either with I. cummingi or (more commonly) 

 with /. sibogae. The series from the coast of Burma is a large one 

 and includes almost every grade in a transition between these two 

 forms, and I have no doubt that the form sibogae must therefore 

 be considered merely as a variety' of I. cummingi, as Hoek himself 

 thought might prove to be the case. Among the specimens that 

 represent this variety in the collection before me are some of those 



