1901.] ON THE AK ATOMY Ol? GRUIPOBM BIRDS, 629 



The genital ducts Were regarded as being quite distinct from 

 -Miillerian ducts in the Granoidei, Crossopterygii, and Teleostei, 

 and to have been developed fi'oiu a condition like that in the 

 Cyclostomata, by a folding-off of a portion of the body-cavity. 

 In those forms in which a connection occurs between the testis 

 and the kidney, the male genital duct was regarded as having been 

 converted into the longitudinal canal of the testicular network. 



The skeleton was entirely cartilaginous at this stage. The 

 chondrocranium and visceral arches were described, and shown 

 to resemble in some respects- those of Elasmobranchi, though 

 Amphibian resemblances were also pointed out. It -was shown 

 that this larva possesses a segmented rod of cartilage attached 

 to the hyoidean arch and forming the axis of the base of the large 

 external gill — 



The development of the vertebral column was shown to be very 

 peculiar, there being at first three series of cartilaginous processes 

 abutting on the notochord on either side. Later, the ventral 

 series lose their connection with the notochord, and become the 

 heads of the ventral ribs. 



The condition of the pectoral fins at this stage wasshown to 

 support the view that these have been derived from a uuiserial 

 fin of the Elasmobranch type, rather than from a biserial 

 archipterygium. 



In general, the structure of this larva was regarded as showing 

 that -.the Crossopterygii at the present day are a central group 

 -:intermediate between the Elasmobranchi, the Teleostei, and the 

 •Amphibia. 



This Memoir will be published entire in the ' Transactions.' ■ 



The fpllowing papers were read : — 



1. On the Anatomy of Gruiform Birds; with special reference 

 to the Correlation of Modifications. By P. Chalmers 

 Mitchell, M.A., D.Sc. Oxon., F.Z.S., Lecturer on 

 Biology at the London Hospital Medical College, 

 University of London. 



[Received December 17, 1901.J 



- : ■ (Text-figures 70-85.) . . : ,■ 



■, In this memoir I use the term Gruiform, descriptively, in the 

 sense of Gadow (4) to denote the JRaUidse, Gruidse, Dicholophidae, 

 Otididie, Rhinpchetidae, Eurypygidae, and Heliornithidae. I have 

 been able to dissect members of all these groups in the Prosectorium 

 of this Society ; and I am specially indebted to my friend Mr. P. 

 E. Beddard, F.R.S., the Prosector, not only for the kindness 

 with which he has given me his personal assistance in verifying 

 many doubtful points, but for the complete manjier.'JLh which he 



