31 



ON THE MORPHOL()(fr OF THE CAUDAL GILLS OF 

 THE LARY.^] OF ZYGOPTERTl) DRAGONFLTES. 



TxTHODUCTioN, Paht i. (Gexkral Morphology), and Part ii. 



(Studip:s ok thk Separate Types). 



By R. J. TiLLYARD, M.A., B.Sc, F.L.S., F.E.S., Linnean 



Macleay Fellow of the Society in Zoology. 



(Plates i.-vi.; and 32 Text-figs.). 



Index. 



iNTRODrCTTON 



Part i. — (Ie.nkkai. MoRrn«)LO(}V of the (tIij.s. 

 Historical Summaiy 



Material Studied 



Methods of Study 



Nature of the Caudal dills 



Tbe Hypodennis and Cuticle ... 



The Basal Pieces aud Hreakiiiu-.Toijit 



The Alv^eolar Mesh work ... ... ... .. 



The Internal LamiuH' ... 

 The Blood -Canals 

 The Nervous System 



The Tracheal System 



Part ii. — Stcdtks of the Ski'ar.vtk (Iill-Types 



A. The Saccoid Type 



B. The Triquetro-Quadrate Type 



C. The Lamellai- Type 



a. The Vertical Lamellar Sub-type 

 (i.) The Lest id Form 

 (ii. ) The Af/rionid Form 



</. The Constricted Lamella 



/i The Nodate Lamella 



y The Subnodate Lamella 



8 The Uenodate Lamella 



h. The Horizontal Lamellar Subtype 

 I). The Reduced (Non-functional) Type 

 Bibliography 



Explanation of Al)breviations used in Text-figures and Plates 

 Explanation of Plates ... 



Introduction. 

 In the year 1913, I Ijegan an extended study of the Yarious 

 organs which function as gills in the body of the Dragonfly larva. 

 As is well known, one great division or sub-order of the Odonata 



