1891.] Anatomy, $-c., of Protopterus annectens. 549 



IV. " On the Anatomy and Physiology of Protopterus annectens" 

 By W. N. PARKER, Ph.D., F.Z.S., Professor of Biology in 

 University College, Cardiff. Communicated by W. H. 

 FLOWER, F.R.S. Received May 4, 1891. 



(Abstract.) 



The work which has resulted in the present paper was begun in 

 Freiburg in the summer of 1888, when the author was fortunate 

 enough, owing to the generosity of Professor Wiedersheim, to obtain 

 a number of fresh specimens for examination. As so many interest- 

 ing points presented themselves at an early stage in the research, a 

 short preliminary notice, without illustrations, was published in the 

 following autumn (' Berichte d. Naturforsch. Gesellschaft zu 

 Freiburg i.Br.,' vol. 4, 1888).* 



This notice merely forms the basis of the present paper, in which 

 the whole subject has been worked out in greater detail. A number 

 of new facts are recorded, some of the author's earlier conclusions 

 modified, and the paper illustrated with 11 plates containing 71 

 figures. 



With the exception of certain special details, the structure of the 

 skeleton and of the nervous and muscular systems is not described, 

 the paper consisting mainly of an account of other organs which 

 have not received so much attention from previous observers, and of 

 a comparison of Protopterus with the other genera of Dipnoi, so far 

 as their structure is known, as well as with other Ichthyopsida. 



The author returns his sincere thanks to the Council of the Royal 

 Society for the grant out of which various expenses connected with 

 the investigation were defrayed, as well as to Professor Wiedersheim, 

 not only for the gift of abundant fresh and preserved material, but 

 also for his continued help and advice during the progress of the 

 work. To Professor Howes the author is indebted for many valuable 

 suggestions. 



A number of details with regard to the habits of Protopterus in 

 captivity are given, and reference is made to Stuhlmann's observa- 

 tions with regard to its mode of life under natural conditions. 



The paired extremities, the movements of which are more like 

 those of limbs than of fins, show no connexion with the cheiroptery- 

 gium, and, in spite of their considerable nerve supply, are evidently 

 greatly degenerated structures as regards their free portions. 

 Sensory organs are not present on them, and they therefore cannot 

 have a tactile function. Their distal ends, like the apex of the tail^ 

 are very variable, and can undoubtedly be reproduced when lost by 

 * See also ' Nature,' TO!. 39, p. 19. 



