21 f Dr. David Sharp's Studies tin Rhynchophora. 



it forms a tube through which the median lobe protrudes'. 

 It includes basally the tegmen, but the apical part is 

 entirely membranous and transparent, and is usually 

 omitted in figures, though the tegmen itself is nearly 

 always represented. In the paper by Muir and myself 

 this membranous part is called the second connecting 

 membrane, but we now consider it better to call this mem- 

 branous area the first, and in the figures it is marked im\. 



A very interesting feature is found in the Rhvneho- 

 phorid group of the Calandridae, inasmuch as this mem- 

 branous area is more or less strongly and completely 

 chitinisedj thus becoming to some extent similar to the 

 " body " of the median lobe. In certain forms, referred 

 at present to the group Sphenophorides, the spiculum 

 proceeds from this chitinised part, and the structure then 

 appears to resemble the tegmen. This condition is figured 

 in the Transactions of the Society (1912. pi. 76, fig. 224a).* 

 This condition is instructive, as it shows that a part of 

 the tube that is usually membranous can become chitinised. 

 and that chitinisation is secondary to the membranous 

 condition; a, fact that should not be lost sight of. The 

 term " connecting membranes " is itself objectionable, as 

 it tends to convey the idea that they are of secondary 

 importance, and merely connect the hard parts, while 

 the fact is the integrity of the tube is the primary object 

 of the whole mechanism. 



Proceeding basally along the tube we come to a 

 chitinous structure of a more or less transverse nature, 

 but differing greatly in the various forms of Rhyncho- 

 phora ; sometimes it forms a simple ring, at others an 

 incomplete ring, but it is usually provided ventrally with 

 a single strut projecting basad. This hard part of the 

 circumference of thetegminal layer is the " tegmen " (Sharp 

 and Muir), the " Gabel " of Lindeman, VerhoefT and Nusslin. 

 It is of great taxonomic importance, especiallv in the 

 families df Rhynchophora that are separated from the 

 Curculionidae ; the parr that is dorsal taking on there a 

 great development (Anthribidae, Brenthidae, Rhynchitidae, 

 Microceridae, Brachyceridae, Belidae, Apionidae, A.ttela- 

 !>i>h/c). all of which have a large " cap-piece," differing in 

 form according to the family. In various forms of Cur- 

 culionidae there is no cap-piece, this being, of course, the 



* In tli'> explanation of the plate this pari is said to be the tegmen, 

 which is an error: for -'tegmen " read there " pseudo-tegmen." 



