BY R. J. TILLYARD. 93 



eight set (Fig. 4). Here the chitin surrounds both the teeth 

 in the set. 



The tendency, shewn especially in gizzard No. 2, to form a 

 longitudinal set of teeth, is of great interest. Amongst 

 Aniso'ptera, the longitudinal field, containing a large number 

 of nearly equal teeth, is a characteristic of the Gom/plnnft. 

 only. In this respect, then, we may regard Petalura as 

 shewing a connection with some distant ancestor of the 

 Gojiiphituv. But the difference between the two forms of 

 gizzard is far moi'e striking than this slight similarity, and 

 strongly bears out the claim that the Petdhirino' should be 

 regarded either as a very detached subfamily, or possibly 

 be raised to the dignity of a family. 



In a kindly criticism of my former paper on the Fetahira 

 exuviae. Dr. Ris pointed out to me that there was nothing 

 remarkable about the position of the involucre of the inferior 

 appendage in the male I'etdlura nymph, as it is interpreted 

 by morphologists to be part of the tergite of the eleventh 

 abdominal segment in A iiisopfcra. Hence it should be found 

 above the anal opening, and not below^ it ; and this is actually 

 the case. As the two involucres of the superior appendages 

 are also morphologically portions of the eleventh tergite, 

 there is nothing really remarkable in the inferior involucre 

 appearing above and between them. He also pointed out to 

 me that I missed a point of great interest, in not studying 

 closely the anal end of the Fetahira nymph ; for the three 

 caudal spines usually conspicuous in nymphs of Animptera, 

 are here reduced to small plates, which together form a fairly 

 distinct and compact eleventh segment. In Fig. 6 of the 

 Plate in my former paper (These Proceedings, 1909, PI. 

 xxiv.) their position is not well shewn. It woiild be better 

 to examine the anal end of a female larva, in which the 

 involucres of the imaginal appendages take up much less 

 room than in the male. Such a sketch, shewing the ivide- 

 open anal opening, with the three plates completely enclos- 

 ing it (f)ne superior and tiro inferior, corresponding to the 



